专业英语课后答案(清华)--王朔中.doc
U n i t1E x e r c i s e s
(1)T r a n s l a t e t h e f o l l o w i n g s e n t e n c e s i n t o C h i n e s e.
1.As with series resonance, the greater the resistance in the
circuit the lower the Q and, accordingly, the flatter and broader the resonance curve of either line current or circuit impedance.
对于串联谐振，电路中的电阻愈大Q值就愈低，相应地线路电流或电路阻抗的谐振曲线也就愈平、愈宽。
2.A wire carrying a current looks exactly the same and
weighs exactly the same as it does when it is not carrying a current.
一根带电的导线其外表与重量都与不带电导线完全一样。
3.Click mouse on the waveform and drag it to change the
pulse repetition rate, or directly enter a new value of the period in the provided dialogue box, while keeping the pulse width unchanged.
在波形上点击鼠标并拖动来改变脉冲重复频率，或者在提供的对话框中直接输入新的周期值，而保持脉冲宽度不变。
4.Electronics is the science and the technology of the
passage of charged particles in a gas, in a vacuum, or in a semiconductor. Please note that particle motion confined within a metal only is not considered electronics.
电子学是一门有关带电粒子在气体、真空或半导体中运动的科学技术。注意，在本书中粒子运动仅限于金属的情况不属于电子学。
5.Hardware technologies have played vital roles in our
ability to use electronic properties to process information, but software and data processing aspects have not developed at the same speed.
硬件技术在我们使用电子特性来处理信息的能力中一
直起着重要作用，而软件及数字处理方面却没能与硬件同步发展。
6.However, in a properly designed DC amplifier the effect of
transistor parameter variation, other than Ico, may be practically eliminated if the operation point of each stage is adjusted so that it remains in the linear operation range of the transistor as temperature varies.
然而在设计得当的直流放大器中，若调节每一级的工作点使之在温度变化时保持在晶体管线性区，就能在实际上消除Ico以外的晶体管参数变化所造成的影响。(2)F i l l i n t h e b l a n k s w i t h t h e m o s t a p p r o p r i a t e c h o i c e.
1.A message signal can any amplitude value
between 0 and A volts.
A. assume
B. use
C. receive
D. accept
2.Each time a positive clock edge occurs, the flip-flop
changes state, leading to half as many pulses at the output to the clock input.
A. as
B. compared
C. due
D. so as
3.In the previous section we discussed sine-wave or CW
modulation systems in which the modulating signal _______ of a digital pulse train.
A. made
B. consisted
C. contained
D. got
4.In this book we shall emphasize the limitations imposed
on the information transmitted by the system through which it was _______ and shall attempt some comparison of different systems.
A. put
B. traveled
C. passed
D. viewed
5.This signal either does not change, or it changes ______
by an amount equivalent to one or more quantum steps.
A. interruptedly
B. rudely
C. abruptly
D. absolutely
6.We shall only be _______ with logical representations, not
absolute values
A. interested
B. caring
C. referred
D. concerned
(3)C h o o s e t h e p h r a s e t h a t i s c l o s e s t i n m e a n i n g t o t h e u n d e r l i n e d p a r t.
1.It is all too easy with linear circuits, which appear
relatively simple when compared with today’s complex logic arrangements, to ignore detailed performance parameters which can drastically reduce the expected performance.
A. which has bad influence upon the system performance
B. which is important to ensure circuit linearity
C. which is possible to enhance the system performance
D. which is crucial for maintaining the desired
performance
2.Therefore there will be a slight time delay, due to the
propagation delay of the flip-flops between the time one flip-flop changes state and the time the next one changes state, i.e., the change of state ripples through the counter, and these counters are therefore called ripple counters.
A. the state change is propagated through the counter like
ripples
B. the state changes cause ripples in the counter
C. passing through the counter, the state ripple changes
D. the state of the counter changes due to ripples
3.Instead of triggering on each pulse, a phase lock technique
examines the relative phase between each oscillator and many of its sync pulses and adjusts oscillator frequency so that the average phase discrepancy is small.
A. checks each oscillator for many sync pulses
B. checks the phase relationship between individual
oscillators and a collection of sync pulses
C. looks at the relations between the phase and the sync
pulses
D. examines whether the phase is relative to the oscillator
and the sync pulses
4.By keeping the off state slightly below threshold, the delay
between the applied electrical pulse and the resulting
optical output pulse is minimized; this delay must indeed not be more than the bit interval so that the optical pulse can accurately reproduce the input signal.
A. ensuring that the system is off the threshold by a small
margin
B. maintaining the system’s shut-down state somewhat
below a prescribed level
C. making sure the system is below its threshold so that the
state is kept off
D. keeping the system in a shut-down state that is under a
given level with a tiny tolerance
5.If the original signal is well behaved, the local oscillator
will need very little information to be able to track, and that information can be obtained by averaging for a long period of time, thereby eliminating noise that could be very large.
A. the LO will not require any information in order to keep
tracking
B. the LO will make use of tracking information that is
scarce in the system
C. the LO will require some information, but not much, so
that the system can track
D. the LO will use no information other than some little
one to maintain tracking
6.The third section describes quantization schemes that take
account of the characteristics of speech.
A. take measure of the speech characteristics
B. take the speech characteristics into consideration
C. count the speech characteristics
D. make use of the speech characteristics
7.In a properly designed DC amplifier the effect of transistor
parameter variation may be practically eliminated if the operating point of each stage is adjusted so that it remains in the linear operation range of the transistor as temperature varies.
A. the effective variation of the transistor parameters
B. the effort to change transistor parameters
C. the transistor parameters that effectively change
D. the results caused by transistor parameter changes
8.Stability and repeatability are fundamental attributes of
digital circuits, however, and the necessary accuracy can be obtained in a digital version of the modulator by an appropriate choice of word length to represent the signals.
A. by expressing the signals with a suitable word length
B. by using a word long enough to describe the signals
C. by choose to characterize the signals in terms of word
length appropriately
D. by appropriately representing the signals to choose a
length of words
U n i t2E x e r c i s e s
(1)T r a n s l a t e t h e f o l l o w i n g s e n t e n c e s i n t o C h i n e s e.
1.If analog signals are to be transmitted digitally, they first
have to be sampled at a specified rate and further converted to discrete amplitude samples by quantization.
如果要以数字方式传输模拟信号，首先必须以一定的频率对信号进行采样，然后通过量化进一步将它们转换为离散的幅度样本。
2.Linear filters amplify or attenuate selected spatial
frequencies, can achieve such effects as smoothing and sharpening, and usually form the basis of re-sampling and boundary detection algorithms.
线性滤波器放大或衰减选择的空间频率，能够实现像
平滑和锐化这些效果，通常是重采样和边缘检测算法
的基础。
3.Stability and repeatability are fundamental attributes of
digital circuits, however, and the necessary accuracy can be obtained in a digital version of the modulator by an appropriate choice of word length to represent the signals.
不过稳定性和可重复性是数字电路的基本性质，在数字式调制器中必要的精度可通过适当地选择代表信号的字长而获得。
4.The first observation is made on the fundamental
relationship between the nature of system and the periodicity of its frequency response: a continuous system has an aperiodic frequency response, while a discrete system has a periodic frequency response.
从系统性质和它频率响应的周期性之间的基本关系中首先可以看到：连续系统有非周期性的频率响应，而离散系统有周期性的频率响应。
5.The main function of the receiver is to extract the input
message signal from the degraded version of the transmitted signal coming from the channel.
接收器的主要功能是从由信道传输来的退化了的信号中提取出输入消息。
(2)C h o o s e t h e w o r d o r p h r a s e t h a t i s c l o s e s t i n m e a n i n g t o t h e u n d e r l i n e d p a r t.
1.Roughly speaking, the transistor can be likened to an
electronically controlled valve whereby energy applied to one connection of the valve enables energy to flow between two other connections.
A. related
B. linked
C. analogized
D. viewed
2.While third party design tools were available, there was
not an effective link from the third party design tools to the layout and actual semiconductor process performance characteristics of the various ASIC manufacturers.
A. When
B. Although
C. As
D. Since
3.These steps, implemented with a level of skill common in
the industry, almost always produce a final device that correctly implements the original design, unless flaws are later introduced by the physical fabrication process.
A. practiced using skills generally available in the industry
B. commonly performed at levels of skilled personnel in
the industry
C. realized with the skillful common level in the industry
D. carried out by skills commonly used in the industry
4.A second major step would be to develop design
specifications that consider the functionality of the human with the same degree of care that has been given to the rest of the system.
A. develop design procedures to account for the human
behavior and activities
B. promote design arrangements and take the human
factors into consideration
C. make used of design steps that respect the human
functionality
D. draft and effect design requirements that take into
account the human functionality
5.Click mouse on the waveform and drag it to change the
pulse repetition rate or directly enter a new value of the period in the provided dialogue box, keeping the pulse width unchanged.
A. simply type a new period value in the given dialogue
box
B. direct an entry for the new period value to the dialogue
box
C. point a straightforward new period value to the dialogue
box provided
D. enter a direction of a new period value to provide a
dialogue box
https://www.wendangku.net/doc/a51023328.html,pared with most of the textbooks at the introductory
level of RF analog design, this book presents some hands-on experiences on the design issues that really work and has been proved by manufactured chips.
A. this book provides some experiences at hand on the
issues encountered in design
B. this book provides some actually working experiences
about the design problems
C. this book presents some available experiences over the
design problems
D. this book presents some issues concerning design
experiences that are handed over
7.For a decade there has been a search for a programmable
processor which, given the cost and volume constraints, is general enough to be programmed with different algorithms.
A. with controlled measures of price and magnitude
B. given the condition of risk and number
C. given the constants of charge and weight
D. given the limits of price and size
8.In a properly designed DC amplifier the effect of transistor
parameter variation, other than Ico, may be practically eliminated if the operating point of each stage is adjusted so that it remains in the linear operation range of the transistor as temperature varies.
A. transistor
B. amplifier
C. Ico
D. parameter
Unit 3 Exercises
(1)T r a n s l a t e t h e f o l l o w i n g s e n t e n c e s i n t o C h i n e s e.
1.A very commonly used method of microwave
measurements is based on the study of a standing wave pattern formed along the line because of the interference of incident and reflected waves.
一个很常用的微波测量方法是基于对驻波图型的研究，这种驻波是由入射波和反射波之间的干涉而沿着传输线形成的。
https://www.wendangku.net/doc/a51023328.html,putations show a reduction of 6dB in the EM field
intensity with the distance doubled, and an increase of 3dB in the intensity with the transmitted power doubled. This result provides verification to the algorithm used.
计算表明，当距离增大一倍时，电磁场强度减小6分贝；
而发射功率增大一倍时，场强则增加3分贝。这一结果验证了所用算法的正确性。
3.Like transfer of heat by conduction, convection and
radiation, microwave heating can be considered as another mode of heat transfer, in which heat is produced directly at the location of the dielectric losses.
就像通过传导、对流、辐射来传递热量一样，微波加热可以看作热传递的另一种方式，即热量直接产生于发生介电损耗的地方。
4.Operation of the radar is based on the measurement of the
time it takes for a pulse transmitted from an antenna to get reflected by the object to be detected and to return at the antenna and the receiver.
雷达的工作是基于对天线发出的脉冲被所要探测的目标反射，（然后）回到天线和接收机所需时间的测量。
5.Other motivations for using CAD in circuit design includes
the wish to acquire confidence in a design that was accomplished by other means, and, not least in importance,
a sense of curiosity or perhaps a desire to discover the
unexpected.
在电路设计中使用CAD的其它动机包括：想要验证用别的方法设计出来的电路；满足好奇心或者可能是想发现预想不到的现象。后一个动机并非是最不重要的。（取得信心，并非最不重要，意料之外的事）
6.The spacing between the repeating amplifiers is a function
of the cable attenuation and the system bandwidth so that the gain provided by these amplifiers compensates for the loss introduced by the cable.
中继放大器之间的间距是电缆衰减和系统带宽的函数，以便这些放大器提供的增益补偿电缆引起的损耗。
7.When the cut-off frequency is no less than the maximal
frequency of the original signal, nor is it greater than the
difference between the sampling frequency and the maximal frequency, the original signal may be completely rebuilt.
当截止频率不小于原始信号的最高频率，也不大于采样频率和最高频率之差，原始信号可以完整地重建。
8.While the politics of the last one hundred years centered
around Industrial Age technology, the politics of the future will be based on Information Age concerns oriented towards the storage, protection and exchange of information.
尽管近百年来的政治活动是以工业时代的技术为中心的，未来的政治活动将基于信息时代的事物，面向信息的存储、保护和交换。
(2)C h o o s e t h e w o r d o r p h r a s e t h a t i s c l o s e s t i n m e a n i n g t o t h e u n d e r l i n e d p a r t.
1.If these other charges and currents are comparable in size
to the sources producing the above electromagnetic field, then a new net electromagnetic field will be produced.
A. make comparison with the size of the sources
B. are compared with the size of the sources
C. have similar size to the sources
D. take a common size of the sources
2.This range of wavelengths has led many to question the
naming convention used for microwaves as the name suggests a micrometer wavelength.
A. has raised many questions about the naming habit
B. has caused many people to challenge the naming rules
C. has led many questions of the naming convention
D. has resulted in many problems in the naming tradition
3.NASA worked in the 1970s and early 1980s to research the
possibilities of using Solar Power Satellite (SPS) systems with large solar arrays that would beam power down to the Earth’s surface via microwaves.
A. shed solar energy to the Earth’s surface from the
satellite
B. set the satellite down to the Earth’s surface with power
C. shut down the power on (to) the Earth’s surface from
the satellite
D. switch off power to the Earth’s surface from the satellite
4.As DoD urgently wanted military command and control
networks that could survive a nuclear war, ARPA was charged with inventing a technology that could get data to its destination reliably even if arbitrary parts of the network disappeared without warning as a result of a nuclear attack.
A. win a nuclear war
B. be used in preparation of a nuclear war
C. avoid a nuclear war
D. be still operational after a nuclear war
5.At the present, state of the art microwave amplifiers and
oscillator tubes can operate in a frequency range up to 40GHz and solid-state microwave devices up to 100GHz.
A. recent and most advanced
B. high tech related
C. sophisticated
D. artistically manufactured
6.In such a fiber rays traveling at larger angles with respect
to the axis have to traverse a longer path and hence take a longer time than those rays which propagate with smaller angles to the axis.
A. have transmitted over a longer distance
B. are bound to treat a longer way
C. must travel through a longer route
D. must deal with a longer trace
7.By keeping the off state slightly below threshold, the delay
between the applied electrical pulse and the resulting optical output pulse is minimized; this delay must indeed not be more than the bit interval so that the optical pulse can accurately reproduce the input signal.
A. this delay must indeed be no more than one internal bit
B. indeed, this delay must exceed the bit of interval
C. as a matter of fact, this delay interval must be a little bit
less
D. this delay must indeed be kept less than the spacing
between data bits
https://www.wendangku.net/doc/a51023328.html,putations show a reduction of 6dB in the EM field
intensity with the distance doubled, and an increase of 3dB in the intensity with the transmitted power doubled. This result provides verification to the algorithm used.
A. that, with a 6dB reduction, the EM field intensity is
twice as strong
B. that the EM field intensity is decreased by 6dB as the
range is doubled
C. that, in the EM field, intensity with double distance
leads to a 6dB reduction
D. a 6dB intensity reduction causes a double distance in
the EM field
U n i t4E x e r c i s e s
(1)T r a n s l a t e t h e f o l l o w i n g p a s s a g e s i n t o C h i n e s e.
https://www.wendangku.net/doc/a51023328.html,munication may be broadly defined as the transfer of
information from one point to another. When the information is to be conveyed over any distance a communication system is usually required. Within a communication system the information transfer is frequently achieved by superimposing or modulating the information on to an electromagnetic wave which acts as a carrier for the information signal. This modulated carrier is then transmitted to the required destination where it is received and the original information signal is obtained by demodulation. Sophisticated techniques have been developed for this process by using electromagnetic carrier waves operating at radio frequencies as well as microwave and millimeter wave frequencies. However, communication may also be achieved by using an electromagnetic carrier that is selected from the optical range of frequencies.
通信可以广义地定义为从一处到另一处的信息传递。当要将信息传输到任何距离以外时就需要有一个通信系
统。在通信系统内部，信息的传输经常通过将信息叠加或调制到作为信号载体的电磁波上来实现。经调制的载波然后被传送到要求的目的地，在那里被接收，原始信号通过解调被恢复出来。为了实现这一过程，已经利用工作在射频、微波以及毫米波频率上的电磁载波开发了复杂的技术。不过通信也可以用光波频段上的电磁载波来实现。
2.Electronic communications is the transfer and movement
of data between locations through the use of computers. An electronic communication system includes the equipment needed to support the movement of information, the communication lines and media to carry the information, the computer software and programs to control the flow of information, the personnel to plan, implement, and operate communications, and the management of all these resources. Electronic communications establishes links between people as well as computers.
电子通信就是通过使用计算机在不同的地点之间传输数据。一个电子通信系统包括：支持信息流动所需要的设备，承载信息的通信线路和媒介，控制信息流的计算机软件和程序，计划、实施、操作通信系统的人员，以及对所有这些资源的管理。电子通信建立起人和人、计算机和计算机之间的联系。
3.First generation communications systems can be
characterized by the use of analog transmission techniques, and the use of simple multiplex access techniques such as frequency division multiple access (FDMA). They suffered from a low user capacity, and security problems due to the simple radio interface used. Second generation systems were introduced in the early 1990’s, and all use digital technology. This provided an increase in the user capacity of around three times, achieved by compressing the voice waveforms before transmission. Third generation systems are an extension on the complexity of second-generation systems and are to be introduced after the year 2000. The
system capacity will be increased to over ten times original first generation systems, achieved by using complex multiplex access techniques such as code division multiplex access (CDMA), or an extension of TDMA, and by improving flexibility of services available.
第一代通信系统以模拟传输技术和简单复用技术如频分复用为特征。这些系统用户容量低，而且因为使用简单的无线电接口而存在安全问题。第二代通信系统于20世纪90年代初开始引入，全部使用数字技术。通过在传输前将话音波形压缩使得用户容量提高了三倍。第三代通信系统是对第二代系统在复杂性方面的扩展，预计于2000年以后启用。通过使用复杂的复用技术如CDMA 或TDMA的扩展，并提高服务的灵活性使得系统容量比原来的第一代系统提高10倍。
4.For each combination of communication
(modulation/detection) type, channel fading model, and diversity type, the average bit error rate (BER) and/or symbol error rate (SER) of the system is obtained and represented by an expression in a form that can readily be evaluated. All cases considered correspond to real practical channels, and in many instances the BER and SER expressions obtained can be evaluated numerically on a hand-held calculator.
对于通信（调制/检测）类型、信道衰落模型、分集类型的每一种组合，得到系统的平均误码率（BER）和符号错误率（SER），并以容易求值的形式表示。所有考虑的相应于实际信道的情况，以及许多情况下得到的BER和SER表达式均可用手持计算器来计算。
5.Modulation is the systematic variation of some attribute of
a carrier waveform such as the amplitude, phase, or
frequency in accordance with a function of the message signal. It is used in communication systems for matching signal characteristics to channel characteristics, for reducing noise and interference, for simultaneously transmitting several signals over a single channel, and for
overcoming some equipment limitations. A considerable portion of this book is devoted to the study of how modulation schemes are deigned to achieve the above tasks.
The success of a communication system depends to a large extent on the modulation.
调制是载波波形的某些属性，例如幅度、相位和频率，根据消息信号的函数有规则的变化。它用于通信系统以使信号特性匹配信道特性，减少噪声和干扰，在单个信道上同时传输多个信号，并克服某些设备的限制。本书相当大部分内容是研究如何设计调制方案以实现上述任务。一个通信系统的成功很大程度上依赖于调制。(2)C h o o s e t h e w o r d o r p h r a s e t h a t i s c l o s e s t i n m e a n i n g t o t h e u n d e r l i n e d p a r t.
1.The receiving device would have the wrong time that had
been agreed in the protocol for sending/receiving data, so some bytes could become corrupted by losing bits.
A. that had been consistent with the protocol of data
exchange
B. that had been the same as the protocol for
sending/receiving data
C. that had been in agreement with the protocol of data
transmission
D. that had been defined in the data transmission protocol
2.Synchronous transmission uses no start and stop bits but
instead synchronizes transmission speeds at both the receiving and sending end of the transmission using clock signals built into each component.
A. using synchronization signals to build each component
B. using timing pulses that are incorporated in each
component
C. using timing signals in order to build each component
D. using clocks that can build signal components
https://www.wendangku.net/doc/a51023328.html,rmation theory, however, does not involve message
importance or meaning, as these are matters of the quality of data rather than the quantity of data, the latter of which is determined solely by probabilities.
A. which is the later one of the determined probabilities
B. the later one being probably deterministic
C. in which the later one is deterministic rather than
probabilistic
D. the data quantity being determined by probabilities only
4.Any small deformations in the height or width of the
pulses are irrelevant since it is only necessary to know whether the pulse is present or absent in order to retrieve the original message.
A. to reform the original information
B. to recover the original signal
C. to re-obtain the original information
D. to represent the original signal
5.Consequently, electronic equipment is constantly subjected
to unwanted sources of energy and is constantly producing energy that adjacent equipment is not designed to accept.
A. continually making unaccepted interference to adjacent
equipment
B. continuously causing neighboring equipment not to
accept expected energy
C. constantly producing energy that is acceptable only to
neighboring equipment
D. ceaselessly generating energy that is considered
acceptable in the design of adjacent equipment
6.Earlier we introduced the concept that the identity of an
amplitude modulated message signal may under certain circumstances be communicated by transmitting regular samples of the message, rather than the continuous signal.
A. may transmit samples that are regular in
communications under some conditions
B. may be in the circumstances that regular message
samples are communicated
C. may be conveyed by sending signal sampled at regular
intervals under some conditions
D. may communicate with certain customers by sending
regular samples of the message
7.For each of the building blocks of the RF transceiver,
which has been broken into separate chapters, a list of essential reference publications also guarantees depth and
academic value of the research achievements presented.
A. each of the basic components of the RF transceiver
B. each of the groups that are built into the RF transceiver
C. the individual elements in the RF transceiver
D. each of the buildings that blocks the RF transceiver
8.We are to develop a code such that fewer bits are assigned
to code words representing gray levels having higher probability of occurrence, and vice versa.
A. in other words, gray levels that more frequently occur
are given more bits
B. and more bits are used for gray levels of lower
probability of occurrence
C. otherwise, more bits are needed in the similar case
D. in other words, more probable gray levels require
shorter code words
Unit 5 Exercises
(1)T r a n s l a t e t h e f o l l o w i n g p a s s a g e i n t o C h i n e s e.
OFDM consists of a large number of subcarriers equally spaced in a frequency band, each may be digitally modulated by a same scheme such as PSK, QAM, etc., or by different schemes.
A serially transmitted sequence is divided into a number of sections, each having N symbols, and the N symbols in each section are used to modulate N carriers for simultaneous transmission. Therefore OFDM is essentially a parallel modulation system. When the number of subcarriers is sufficiently large, the system can resist multipath interference. This is because that, in the time domain, a symbol duration longer than the multipath delay can be chosen, while in the frequency domain, each symbol only occupies a small portion of the channel’s frequency band. Thus, the effect of multipath fading spreads over many symbols, resulting in slight distortion to many symbols rather than complete destroy of a few symbols. In this way, correct demodulation is not affected so that the signal can be accurately recovered at the receiver.
In an OFDM system, the principle of choosing the subcarrier interval is to make the subcarriers mutually orthogonal within the entire symbol period. Thus, even if spectral overlap exists between the subcarriers, the symbols can still be recovered without loss. In order to realize maximum spectral efficiency, the interval between subcarriers is usually chosen to equal the reciprocal of the symbol duration T . Therefore the subcarrier frequencies in the base band are f n = n /T , (n = 0, 1, ... , N -1). Denoting the n -th modulating symbol as X (n ), the OFDM waveform within a symbol duration can be expressed as: T
t t T n j n X t x N n <≤??? ??=∑-=0,2exp )()(1
0π
(1) Sampling this waveform at t = T /N yields 1,,2,1,2exp )(2exp )()(1
01
0-=???
??=??? ??=∑∑-=-=N k N nk j n X N kT j n X k x N n N n ππ
(2)
It is observed from the above expression that x (k ) and X (n )
form a discrete Fourier transform pair, therefore the baseband OFDM waveform can be generated from the discrete Fourier transform of N modulating symbols. When N =2m where m is an integer, the fast algorithm of IDFT is easy to implement.
OFDM 由大量在频率上等间隔的子载波构成。每个子载波可用同样的方案，如PSK ，QAM 等，或者用不同的方案数字调制。将串行传输的符号序列分成许多段，每一段有N 个符号，每段的N 个符号被用来分别调制N 个载波同时发送。因此，OFDM 本质上是一个并行调制系统，当载波数足够大时，这种系统具有抗多径干扰的能力。这是因为在时域上符号周期能选取得比多径延迟时间长，而在频域上每个符号只占整个信道带宽的一小部分，因此多径衰落的影响被分散到许多符号上，其结果是许多符号都发生轻度的畸变，而不是使某些符号被完全破坏。这样，不影响正确的解调，信号能在接收器中准确地恢复。
在OFDM 系统中，选择子载波间隔的原则是使子载波在整个符号周期内相互正交，这样。即使在子载波间存在频谱部分重叠，符号仍能无损失地恢复。为了实现最大的频谱效率，子载波之间的间隔通常选取为符号周期的倒数。因此基带子载波频率为f n = n /T , (n = 0, 1, ... , N -1)，第n 个调制符号记为X (n )，在一个符号周期内的OFDM 波形可表示：
T t t T n j n X t x N n <≤??? ??=∑-=0,2exp )()(10π (1) 在t = T /N 时刻采样这个波形得到：
1,,2,1,2exp )(2exp )()(1010
-=??? ??=??? ??=∑∑-=-=N k N nk j n X N kT j n X k x N n N n ππ (2) 从上面的表示中可以看到，x (k ) 和X (n )构成了一对离散傅里叶变换，因此基带OFDM 波形可根据N 个调制符号的离散傅里叶变换来生成。当N =2m ，其中m 为整数，IDFT 的快速算法很容易实现。
(2) C h o o s e t h e w o r d o r p h r a s e t h a t i s c l o s e s t i n m e a n i n g t o t h e u n d e r l i n e d p a r t .
1. The process gain of a system indicates the gain or signal to
noise improvement exhibited by a spread spectrum system by the nature of the spreading and despreading process.
A. by virtue of the spreading/dispreading process
B. by processing the spreading/despreading naturally
C. according to the spreading/despreading characteristics
D. using the natural spreading/dispreading process
2. Due to the unavoidable timing errors between the users,
there is little point in using Walsh codes as they will no longer be orthogonal.
A. using Walsh codes will have some point due to the absence of orthogonality
B. using Walsh codes is meaningless since orthogonality
will not exist any more
C. Walsh code cannot be used since they are not
orthogonal
D. it is unnecessary to use Walsh codes because
orthogonality is lost
3. For example, when a part of the channel bandwidth is
faded, frequency interleaving ensures that the bit errors that would result from those subcarriers in the faded part of the bandwidth are spread out in the bit-stream rather than being concentrated.
A. that would be produced in those subcarriers suffering
from frequency selective fading
B. that would cause some subcarriers being faded in some
part of the bandwidth
C. that would came from the fading subcarriers falling in
part of the bandwidth
D. that would result in those faded subcarrier of the part of
the bandwidth
4.The basic idea of applying the beamformer technique to
this approach is very promising and might give a significant improvement for source localization.
A. might obtain formidable gain in local sources
B. provide possibilities to substantially enhance source
locations
C. might present a major advance in localizing sources
D. is likely to considerably refine techniques to locate
sources
5.Early we introduced the concept that the identity of an
amplitude modulated message signal may under certain circumstances be communicated by transmitting regular samples of the message, rather than the continuous signal.
A. values of the message signal taken at regular intervals
B. formally obtained message samples
C. samples of the message produced in a specific manner
D. samples of the regularly obtained message
6.Having defined these functions, we will proceed to show
how they can be used to evaluate certain integrals characteristic of system error performance.
A. evaluate characteristics of certain integrals in system
error performance
B. assess certain integrals that are typical in describing
error performance of the systems
C. decide the value of some characteristic integrals of error
performance of the systems
D. carry out evaluations on the integrated characteristics of
system error performance
7.Modulation is the systematic variation of some attribute of
a carrier waveform such as the amplitude, phase, or
frequency in accordance with a function of the message signal.
A. in terms of a message carried by the signal
数学专业英语
数学专业英语课后答案
2.1数学、方程与比例 词组翻译 1.数学分支branches of mathematics，算数arithmetics，几何学geometry，代数学algebra，三角学trigonometry，高等数学higher mathematics，初等数学elementary mathematics，高等代数higher algebra，数学分析mathematical analysis，函数论function theory，微分方程differential equation 2.命题proposition，公理axiom，公设postulate，定义definition，定理theorem，引理lemma，推论deduction 3.形form，数number，数字numeral，数值numerical value，图形figure，公式formula，符号notation(symbol)，记法/记号sign，图表chart 4.概念conception，相等equality，成立/真true，不成立/不真untrue，等式equation，恒等式identity，条件等式equation of condition，项/术语term，集set，函数function，常数constant，方程equation，线性方程linear equation，二次方程quadratic equation 5.运算operation，加法addition，减法subtraction，乘法multiplication，除法division，证明proof，推理deduction，逻辑推理logical deduction 6.测量土地to measure land，推导定理to deduce theorems，指定的运算indicated operation，获得结论to obtain the conclusions，占据中心地位to occupy the centric place 汉译英 （1）数学来源于人类的社会实践，包括工农业的劳动，商业、军事和科学技术研究等活动。 Mathematics comes from man’s social practice, for example, industrial and agricultural production, commercial activities, military operations and scientific and technological researches. （2）如果没有运用数学，任何一个科学技术分支都不可能正常地发展。 No modern scientific and technological branches could be regularly developed without the application of mathematics. （3）符号在数学中起着非常重要的作用，它常用于表示概念和命题。 Notations are a special and powerful tool of mathematics and are used to express conceptions and propositions very often. （4）17 世纪之前，人们局限于初等数学，即几何、三角和代数，那时只考虑常数。Before 17th century, man confined himself to the elementary mathematics, i. e. , geometry, trigonometry and algebra, in which only the constants were considered. （5）方程与算数的等式不同在于它含有可以参加运算的未知量。 Equation is different from arithmetic identity in that it contains unknown quantity which can join operations. （6）方程又称为条件等式，因为其中的未知量通常只允许取某些特定的值。Equipment is called an equation of condition in that it is true only for certain values of unknown quantities in it. （7）方程很有用，可以用它来解决许多实际应用问题。
专业英语课后习题答案
Lesson2 Exercises 1. Put the following into Chinese. （1）Ohm’s law states that the voltage across a resistor is directly proportional to the current flowing through the resistor. The constant of proportionality is the resistance value of the resistor in ohms. 流过电路里电阻的电流，与加在电阻两端的电压成正比，与电阻的阻值成反比。这就是欧姆定律。 （2）Many materials, however, closely approximate an ideal linear resistor over a desired operating region. 不过，许多材料在规定的工作范围内非常接近理想线性电阻。 （3）It should be noted that an ideal voltage source (dependent or independent ) will produce any current required to ensure that the terminal voltage is as stated, whereas an ideal current source will produce the necessary voltage to ensure the stated current flow. 应该注意：一个理想电压源（独立或受控）可向电路提供任意电流以保证其端电压为规定值，而电流源可向电路提供任意电压以保证其规定电流。 （4）A different class of relationship occurs because of the restriction that some specific type of network element places on the variables. Still another class of relationship is one between several variable of the same type which occurs as the result of the network configuration, i. e., the manner in which the various element of the network are interconnected. 一种不同类型的关系是由于网络元件的某种特定类型的连接对变量的约束。另一类关系由于网络结构，即网络的不同元件互相连接的方式所产生的相同形式的一些变量间的关系。 （5）The thermal conductivity of metals is as much as several hundred times that of glass. 金属的导热率比玻璃高几百倍。 （6）Magnetic line of force will，whenever passible, travel through iron or other magnetic materials. 磁力线只要有可能就会通过铁或其它磁性材料。 （7）Actually, 0 o C is indeed the lower limit to temperatures capable of being attained. 事实上绝对零度确是所能达到的温度的最低限度。 2. Translate the following into English. （1）电路元件吸收或释放的功率为元件两端的电压与流过该元件电流的乘积。 The power absorbed or supplied by a circuit element is the product of the voltage across the element and the current through it. （2）理想独立电源是一个有源元件，它所提供的电压或电流不依赖于电路中其他变量。 An ideal independent source is an active element that provides a specified voltage or current that is completely independent of other circuit variables. （3）受控电源是一个有源元件，它所提供的电压或电流受电路中某部分电压或电流控制。 An ideal dependent (or controlled) source is an active element in which the source quantity is controlled by another voltage or current. （4）叠加定理为：线性电路中，任一电压或电流都是电路中各个独立电源单独作用时，在该处产生的电压或电流的叠加。 The superposition principle states that the voltage across (or current through) an element in a linear circuit is the algebraic sum of the voltages across (or current through) that element due to each independent source acting alone. （5）计算机可分为模拟计算机和数字计算机两种。Computers may be classfied as analog and digital．（6）新型晶体管的开关时间缩短了三分之二。The switching time of the new-type transistor is shortened three times． （7）超导体在电气应用上的重要性不能被估计过高。The importance of superconductor in the uses of electricity cannot be overestimated.
会计专业英语重点1
Unit 1 Financial information about a business is needed by many outsiders .These outsiders include owners, bankers, other creditors, potential investors, labor unions, government agencies ,and the public ,because all these groups have supplied money to the business or have some other interest in the business that will be served by information about its financial position and operating results. 许多企业外部的人士需要有关企业的财务信息，这些外部人员包括所有者、银行家、其他债权人、潜在投资者、工会、政府机构和公众，因为这些群体对企业投入了资金，或享有某些利益，所以必须得到企业财务状况和经营成果信息。 Unit 2 Each proprietorship, partnership, and corporation is a separate entity. 每一独资企业、合伙企业和股份公司都是一个单独的主体。 In accrual accounting, the impact of events on assets and equities is recognized on the accounting records in the time periods when services are rendered or utilized instead of when cash is received or disbursed. That is revenue is recognized as it is earned, and expenses are recognized as they are incurred –not when cash changes hands .if the cash basis accounting were used instead of the accrual basis, revenue and expense recognition would depend solely on the timing of various cash receipts and disbursements. 在权责发生制下，视服务的提供而非现金的收付在本期对资产和权益的影响作出会计记录。即，收入是在赚取时确认，费用是在发生时确认——而不是在现金转手时。如果现金收付制替代权责发生制，那么收入和费用仅仅依靠各种现金收付活动的时间确定来确认。 Unit 3 During each accounting year ,a sequence of accounting procedures called the accounting cycle is completed. 在每一会计年度内，要依次完成被称为会计循环的会计程序。 Transactions are analyzed on the basis of the business documents known as source documents and are recorded in either the general journal or the special journal, i. e . the sales journal ,the purchases journal (invoice register ) ,cash receipts journal and cash disbursements journal . 根据业务凭证即原始凭证分析各项交易，并记入普通日记账或特种日记账，也就是销货日记账，购货日记账（发票登记簿），现金收入日记账和现金支出日记账。 A trial balance is prepared from the account balance in the ledger to prove the equality of debits and credits. 根据分类账户的余额编制试算平衡表，借以验证借项和贷项是否相等。 A T-account has a left-hand side and a right-hand side, called respectively the debit side and credit side. 一个T 型账户有左方和右方，分别称做借方和贷方。 After transactions are entered ,account balance (the difference between the sum of its debits and the sum of its credits ) can be computed.
数学专业英语课后答案
2.1 数学、方程与比例 （1）数学来源于人类的社会实践，包括工农业的劳动，商业、军事和科学技术研究等活动。 Mathematics comes from man’s social practice, for example, industrial and agricultural production, commercial activities, military operations and scientific and technological researches. （2）如果没有运用数学，任何一个科学技术分支都不可能正常地发展。 No modern scientific and technological branches could be regularly developed without the application of mathematics. （3）符号在数学中起着非常重要的作用，它常用于表示概念和命题。Notations are a special and powerful tool of mathematics and are used to express conceptions and propositions very often. （4）17 世纪之前，人们局限于初等数学，即几何、三角和代数，那时只考虑常数。 Before 17th century, man confined himself to the elementary mathematics, i. e. , geometry, trigonometry and algebra, in which only the constants were considered. （5）方程与算数的等式不同在于它含有可以参加运算的未知量。 Equation is different from arithmetic identity in that it contains unknown quantity which can join operations. （6）方程又称为条件等式，因为其中的未知量通常只允许取某些特定的值。Equipment is called an equation of condition in that it is true only for certain values of unknown quantities in it. （7）方程很有用，可以用它来解决许多实际应用问题。 Equations are of very great use. We can use equations in many mathematical problems. （8）解方程时要进行一系列移项和同解变形，最后求出它的根，即未知量的值。To solve the equation means to move and change the terms about without making the equation untrue, until the root of the equation is obtained, which is the value of unknown term. 2.2 几何与三角 （1）许多专家都认为数学是学习其他科学技术的必备基础和先决条件。 Many experts recognize that mathematics is the necessary foundation and prerequisite of studying other science technology. （2）西方国家的专家认为几何起源于巴比伦和埃及人的土地测量技术，其实中国古代的数学家对几何做了许多出色的研究。 The western experts think that geometry had its origin in the measurements by the Babylonians and Egyptians of their lands. Infect, the ancient Chinese mathematicians made much remarkable study for geometry. （3）几何的学习使学生在思考问题时更周密和审慎，他们将不会盲目接受任何结论。 In studying geometry, the student is taught to think clearly and critically and he is led away from the practice of blind acceptance of any conclusions. （4）数学培养学生的分析问题的能力，使他们能应用毅力、创造性和逻辑推理来解决问题。
【专业英语课后题答案】 徐鹿专业英语答案
【专业英语课后题答案】徐鹿专业英语答案 Unit 1 The Fundamentals of Computers 1.1 The Varieties of Computers ? III. Translating. – 1. Original : Primary storage, or memory, is the internal computer circuitry that temporarily holds data waiting to be processed. Secondary storage, simply called storage, refers to the devices and media that store data or information permanently. – Translation : 一级存储，或称内存，是临时保存等待被处理数据的计算机内 部电路。而二级存储，简称存储器，是指那些永久性存储数据或信息的设备 和介质。 – 2. Original : A biological nanocomputer, which would be made of DNA and could fit into a single human cell, would use DNA as its software and enzymes as its hardware; its molecular-sized circuits would be viewable only through a microscope. – Translation : 由DNA 制成并能放置在一个单独的人体细胞中的生物学纳米 计算机会利用DNA 作为它的软件，酶作为它的硬件；其具有分子大小尺寸 的电路将只有通过显微镜才能够看见。 1.2 The History of Computers ? III. Translating. – 1. Original : This introduction pought about the first real signs of competition within computing history, which helped to spur faster and better development of computers. – Translation : 这一引入带来了计算历史中可谓第一个真正的竞争标志，有助 于刺激计算机更快 –更好的发展。 – 2. Original : While expensive, these machines started the trend for computers within common households. – Translation : 虽然昂贵，但是这些机器开启了计算机在普通家庭中使用的趋 势。 Unit 2 Computer Hardware 1.1 Computer Motherboard ? III. Translating. – 1. Original : A 2003 study found that some spurious computer crashes and general reliability issues, ranging from screen image distortions to I/O read/write errors, can be attributed not to software or peripheral hardware but to aging capacitors on PC motherboards. – Translation : 2003年的一个研究发现，一些伪劣的计算机损毁和常规可靠性 的问题，从屏幕图像失真到输入/输出读写错误，并不是由于软件或外围硬 件引起的，而是由于PC 机主板上老化的电容器造成的。 – 2. Original : At power-up the central processor would load its program counter with the address of the boot ROM and start executing ROM instructions displaying system information on the screen and running memory checks. – Translation :启动之后，中央处理器将加载记录着引导ROM 地址的程序计数
会计专业英语翻译
. 1. Accounting first is an economic calculation. Economic calculation includes both static phenomenon on the economy's stock of the situation, including the situation of the period of dynamic flow, including both pre-calculated plan, but also after the actual calculation. Accounting is a typical example of economic calculation, calculation of economic calculation in addition to accounting, which includes statistical computing and business computing. 2. Accounting is an economic information systems. It would be a company dispersed into the business activities of a group of objective data, providing the company's performance, problems, and enterprise funds, labor, ownership, income, costs, profits， debt, and other information. Clearly, the accounting is to provide financial information-based economy information systems, business is the licensing of a points, thus accounting has been called "corporate language." 3. Accounting is an economic management.The accounting is social production develops to a certain stage of the product development and production is to meet the needs of the management, especially with the development of the commodity economy and the emergence of competition in the market through demand management on the economy activities strict control and supervision. At the same time, the content and form of accounting constantly improve and change, from a purely accounting, scores, mainly for accounting operations, external submit accounting statements, as in prior operating forecasts, decision-making, on the matter of economic activities control and supervision, in hindsight, check. Clearly, accounting whether past, present or future, it is people's economic management activities.
数学专业英语一次函数专题
“数学专业英语一次函数专题”教学设计 1. 教学内容及解析 教学内容：与直角坐标系及一次函数相关的英语文献资料 内容解析：本节内容应从两个方面去考虑. 一方面，从数学知识的角度，本节所涉及的是从平面直角坐标系到一次函数的数学知识，都是学生学过的基础知识及其应用，是对于这些知识的拉练式复习，并作为后面用英语叙述解答相关问题知识基础；另一方面，从语言的角度，学生会接触到大量没有接触过，但他们却很熟悉的英语词汇及短语，主动学习的学生可以在老师的指导下快速理解其含义并加入到自己的知识体系中，但需要花时间巩固，是需要读、写、说来巩固的内容. 这也正是本节的重点和难点所在. 2. 教学目标及解析 教学目标：①能根据已有的数学知识和给出的单词对照表，将给出的相关数学定理及结论的英语版本翻译为中文；②能理解并解答用英语表述的相关数学问题；③能将解决数学问题的过程用英语进行书面表述；④初步了解用英语表达与直角坐标系及一次函数相关数学理论的范式. 目标解析：学生掌握基本词汇，并能阅读与本节内容相关的英语文献，是学习和使用数学专业英语的最基本要求，学生需要在学习的过程中逐渐由接受，即阅读或聆听，逐渐向输出，即书面和口头表达的方向发展. 为达到此目标，学生需要在课前独立完成对于本节需要的单词的学习，并阅读一系列简短的相关数学文献，并在这个过程中初步体会数学专业英语的表达范式；在课堂上，在教师的指导下对自己的认知进一步补充，并进行一定量的练习，暴露自己的问题，在教师的帮助下修正问题，完善认知. 3. 教学问题诊断分析 学生在进行语言表达时，往往受到母语的限制，对于非母语的表达方式的接受能力一时难以习惯，而数学对于表达能力则有更高的要求，要求叙述简洁、逻辑清晰，因此本教学设计强调学生在有相当阅读量的积累后，通过自主练习，逐渐感受用英语表达数学理论的基本范式. 教师在教学过程中的主要任务在于为学生提供合适的学习资料，在学生学习的过程中给予提示与指导，及时指出学生的问题并予以纠正. 对于语言的学习，阅读量的积累是至关重要的，教师在课堂上的讲解、学生在课堂上的练习，都只是学习的一部分环节，如果需要帮助学生正确掌握表达数学理论的范式，尽量不留死角，就必须保证课前预习和课后复习的有效性，预习复习材料的充足性，这对教师的教学资料的积累和学生自主学习能力，都是一个挑战. 4. 教学支持条件分析 学情条件：初二8班是实验班，学生有较强的学习热情和好奇心，也知道课前预习、课上参与学习活动、课后复习的重要性，在曾经的数学课程教学中，也有一定的课前预习，课堂讨论的传统，对于本教学设计的各个环节，是可以理解教师的用意，并遵循教师的指导进行学习活动. 在知识层面上，学生已经系统学习过一次函数相关的知识，课程中提供的学习资料都是学生熟悉的数学知识；学生在英语学习上，已经有多年的积累，对于英语语法的学
计算机专业英语教程(第四版)习题答案
计算机专业英语教程(第四版)习题答案
计算机专业英语（第四版）课后习题答案 Unit 1 [Ex 1] Fb5E2RGbCAP [Ex 2] 1. input, storage, processing, and output 2. power; speed; 1. F 2. T 3. T 4. F 5. T 6. T 7. T 8. T 9. T 10.
memoryp1EanqFDPw 3. central processing unit memoryDXDiTa9E3d 5. keyboard; [Ex 3] B. A. central processing unit; 1. F 2. D 2. monitor 3. G 4. C 5. B main memory; 6. A 7. E monitorRTCrpUDGiT 8. H5PCzVD7HxA 4. internal; primary;
1. user
3. data
4. keyboard
5. data processingjLBHrnAILg
6. information [Ex 4] instructions
7. computer
8. memory 3. manipulates 4.
1. input device 2. screen, screen 5. retrievexHAQX74J0X 8. Function
6. code 7. hard copy
[Ex. 5] 新处理器开始 IT 技术的新时代 New Processors Open New Era of IT Technologies Last week, Intel introduced to the public in Russia and other CIS countries a family of processors Intel Xeon E5-2600. They are more powerful and reliable and, importantly, are very economical in terms of energy consumption. Their
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专业英语部分习题答案参考
b--吡啶pyridine 巴比妥酸:barbituric acid比电导conductance 不规则的:irregular 崩解剂disintegrant c--萃取extraction 成团:agglomeration 测量仪measurement 肠液:intestinal fluid d--胆固醇cholestero 对映体:enantiomer 电极electrode 代谢:metabolism f--反相渗透reverse osmosis 分布:disposition g--构象:conformation 固化:solidize j--甲苯toluene 静脉注:intravenous injection 挤压:compress 聚集:aggregate 胶囊capsule l--粒子:particle 立体选择性:stereoselectivity 利用率:availability m--灭菌产品sterile products n--粘合剂adhesive p--偏振光:polarized light 片剂tablet 配剂elixir 排泄:excretion q--起始原料starting materials(raw materials) q醛aldehyde r--溶解度:solubility 乳剂emulsion 润滑剂lubricant s--释放:release 渗液solution 生物膜:biologic membrane 生物碱alkaloid, t---糖浆syrup 甜味剂sweetener w--丸剂pill 微生物microorganism 胃液:gastric fluid 稳定态:steady-state x--旋光异构现象:optical isomerism 悬浮液suspension 香味剂flavor 稀释剂diluent 形状:shape 吸收:absorption 消除:elimination y--胰岛素insulin 压片:tablet compression z--中间体intermediate 重结晶recrystallization 左旋:levorotation 蒸馏distillation 组织tissue a--asymmetric carbon不对称碳absorption吸收action动作adhesive粘合剂c--contamination污染chirality:手性compress压缩composite合成的compressibility:可压缩性compaction:压紧contamination specialize特殊污染conductivity电导率control:控制clinical:临床的 d--design:设计dry:干燥delivery:传送 e-- extend:延长epoxide:环氧化物 f-- formulation:制剂fluidity:流动性f unction:功能 g--geometric isomerism:几何异构 h-- hormone激素hydrolysis diastereoisomer:水解非对映异构体 heterogeneous catalyst多相催化剂， i--irrigating冲洗 m-- metabolite代谢物medication药物治疗medicine内服药mill:研磨measure尺寸mix:混合microorganisms微生物 o--ophthalmic眼药 p-- polysaccharide多糖peptide肽plasma血浆penicillin青霉素，precursor:前体partition coefficient:狭义分配系数pharmaceutical制药的parenteral注射药物pycogens热源procedure:程序 q-- quality性质quantity数量 s-- steroid甾类steric effect:空间效应stereoselectivity:立体选择性screening:过筛sustain :维持 t-- treat治疗therapy:治疗 u--uniformity目标v--vaccine疫苗
(完整版)会计专业英语重点词汇大全
?accounting 会计、会计学 ?account 账户 ?account for / as 核算 ?certified public accountant / CPA 注册会计师?chief financial officer 财务总监?budgeting 预算 ?auditing 审计 ?agency 机构 ?fair value 公允价值 ?historical cost 历史成本?replacement cost 重置成本?reimbursement 偿还、补偿?executive 行政部门、行政人员?measure 计量 ?tax returns 纳税申报表 ?tax exempt 免税 ?director 懂事长 ?board of director 董事会 ?ethics of accounting 会计职业道德?integrity 诚信 ?competence 能力 ?business transaction 经济交易?account payee 转账支票?accounting data 会计数据、信息?accounting equation 会计等式?account title 会计科目 ?assets 资产 ?liabilities 负债 ?owners’ equity 所有者权益 ?revenue 收入 ?income 收益
?gains 利得 ?abnormal loss 非常损失 ?bookkeeping 账簿、簿记 ?double-entry system 复式记账法 ?tax bearer 纳税人 ?custom duties 关税 ?consumption tax 消费税 ?service fees earned 服务性收入 ?value added tax / VAT 增值税?enterprise income tax 企业所得税?individual income tax 个人所得税?withdrawal / withdrew 提款、撤资?balance 余额 ?mortgage 抵押 ?incur 产生、招致 ?apportion 分配、分摊 ?accounting cycle会计循环、会计周期?entry分录、记录 ?trial balance试算平衡?worksheet 工作草表、工作底稿?post reference / post .ref过账依据、过账参考?debit 借、借方 ?credit 贷、贷方、信用 ?summary/ explanation 摘要?insurance 保险 ?premium policy 保险单 ?current assets 流动资产 ?long-term assets 长期资产 ?property 财产、物资 ?cash / currency 货币资金、现金
数学专业英语课后答案
2.1数学、方程与比例 词组翻译 1.数学分支branches of mathematics，算数arithmetics，几何学geometry，代数学algebra，三角学trigonometry，高等数学higher mathematics，初等数学elementary mathematics，高等代数higher algebra，数学分析mathematical analysis，函数论function theory，微分方程differential equation 2.命题proposition，公理axiom，公设postulate，定义definition，定理theorem，引理lemma，推论deduction 3.形form，数number，数字numeral，数值numerical value，图形figure，公式formula，符号notation(symbol)，记法/记号sign，图表chart 4.概念conception，相等equality，成立/真true，不成立/不真untrue，等式equation，恒等式identity，条件等式equation of condition，项/术语term，集set，函数function，常数constant，方程equation，线性方程linear equation，二次方程quadratic equation 5.运算operation，加法addition，减法subtraction，乘法multiplication，除法division，证明proof，推理deduction，逻辑推理logical deduction 6.测量土地to measure land，推导定理to deduce theorems，指定的运算indicated operation，获得结论to obtain the conclusions，占据中心地位to occupy the centric place 汉译英 （1）数学来源于人类的社会实践，包括工农业的劳动，商业、军事和科学技术研究等活动。 Mathematics comes from man’s social practice, for example, industrial and agricultural production, commercial activities, military operations and scientific and technological researches. （2）如果没有运用数学，任何一个科学技术分支都不可能正常地发展。 No modern scientific and technological branches could be regularly developed without the application of mathematics. （3）符号在数学中起着非常重要的作用，它常用于表示概念和命题。 Notations are a special and powerful tool of mathematics and are used to express conceptions and propositions very often. （4）17 世纪之前，人们局限于初等数学，即几何、三角和代数，那时只考虑常数。 Before 17th century, man confined himself to the elementary mathematics, i. e. , geometry, trigonometry and algebra, in which only the constants were considered. （5）方程与算数的等式不同在于它含有可以参加运算的未知量。 Equation is different from arithmetic identity in that it contains unknown quantity which can join operations. （6）方程又称为条件等式，因为其中的未知量通常只允许取某些特定的值。Equipment is called an equation of condition in that it is true only for certain values of unknown quantities in it. （7）方程很有用，可以用它来解决许多实际应用问题。