1、信息与通信工程专业英语,第1篇 科技书籍常用语法,（一）It作为形式主语的主语从句,It + be动词（或叫系动词）+过去分词（或形容词）+ that引导的主语从句。1It is well known that 众所周知 例：It is well known that light travels faster than sound.,2It is said that 据说 例：It is said that an asynchronous data link is character-oriented. 3It has been found that 人们已经发现 It has been fo
2、und that noise can be introduced into transmission path in many different ways.,（二）强调句型,1以It开头的强调句型 It +系动词（或be动词）+ 被强调的部分（谓语动词除外）+ which（或that, who）引导的从句。在如下的例句中，被强调的部分用下划线标出。 例1It is the relationship of the true signal to the noise signal, known as the signal to noise ratio, which is of the most i
3、nterest to the communication engineers.,例2It was we who did an experiment on the speed of sound yesterday. 2对于谓语动词的强调 例1PSTN did play an important role in communication industry in the past few decades.,3倒装语序的强调 例1Astounding as these advances may seem, we are only at the beginning of what is possibl
4、e. 例2Each network is only capable of transporting one specific service for which it was intentionally designed. Only in a limited number of cases can it be adapted to other services.,（三）动词不定式,不定式动词= to + 动词原型 不定式动词短语= to + 动词原型 + 宾语（名词，宾格代词，从句等） 1不定式动词短语作主语 例1To understand the characteristics of opt
5、ical fibers will give us an appreciation for what an optical fiber does.,2不定式动词短语作宾语 例1As a system analyst, you will be expected to learn the jargon used by computer salespeople and judge the validity of their sales claims 例2As a user, you have understood how to use the computer effectively.,3不定式动词短
6、语作表语 例1As a system manager, your job is to maximize the efficiency of your systems. 例2The original idea of ARPANET was to increase computing capacity that could be shared by users in many locations and to find out what would happen for computer networks to survive a nuclear war or other disaster.,4不
7、定式动词短语作定语 例1The simplest way to access a file on any Internet machine is to copy it across the net work to your local machine.（在Internet上访问一个文件最简单的办法就是把这个文件复制到你自己的机器上。）此处的动词不定式to access是用来修饰先行词way的。 例2Are you sure there is a real need to replace the older equipment?（你确定要把这台老设备换掉吗？）to replace 在这里修饰名词
8、need。,5不定式动词短语作状语 例1If you have a better understanding of a computer, you will be able to write better programs. 例2Advanced network management and maintenance capabilities are required to (effectively) manage the flexibility provided by SDH,6复合宾语 动词不定式复合宾语= 名词（宾语）+ 不定式动词短语 宾格代词（宾语）+ 不定式动词短语 宾格代词（宾语）
9、+ 形容词+不定式动词短语 例1The students asked the teacher to explain the difficult theory again. 例2Email permits network users to send messages to each other.,（四）分词及分词短语,分词短语=分词（现在或过去） + 名词（或名词词组）+ 分词后置定语+ 介词短语 + 名词（或名词词组）+ 介词短语+ 形容词（或形容词短语）+ 介词短语,例1 AIn the OSI model, there are seven numbered layers. BThe mic
10、robend problems of optical fibers were overcome through the use of cabling techniques. CThe most commonly used network service is electronic mail (E-mail). DThe user should know where the resources locate and also should know some operating commands concerned.,例2 AThe Internet is a giant network of
11、computers located (all) over the world. BThe Internet is an international collection of computer networks connected (together) through backbone systems.,例3 AThey consider that the OSI reference model is the best tool available to teach people about sending and receiving data on a network BFiber opti
12、cs was already a wellestablished commercial technology in 1966 suggesting the use of low loss optical fibers for communication.,例4To address the problem of different network system being incompatible and incapable of communicating with each other. 例5SDH equipment will deliver the flexibility require
13、d by network operators to cost-effectively manage the growth in bandwidth and provisioning of new customer services expected in the next decade.,分词短语还有一些特别的构成方法。 现在分词短语 = 现在分词 + 过去分词 + 介词短语 例：If somebody else had something interesting stored on his or her computer, it was a simple matter to obtain a
14、 copy.,分词在句子中的作用可由下面的例句来说明。 1分词作表语 例1The prospects for the commercial success of IPTV are encouraging. 2分词作定语 例1Normally，a voice channel has a sampling rate of 8 kHz. 例2The Internet is developing at an astonishing speed.,3分词作状语 例1At the receiving end of an asynchronous serial data link, the receiver
15、 continuously monitors the link looking for a start bit. 例3In message switching, messages travel independently and asynchronously, finding their own way from source to destination.,4动词的ing 形式作主语或宾语 例1In GSM system, roaming is fully automatic between and with all countries covered by GSM system. 例2Ti
16、ming is the most critical aspect of an asynchronous system. 5分词短语构成复合宾语 复合宾语 = 宾语（名词或宾格代词）+ 分词短语 例1Nowadays, you may find a cellular mobile telephone system being developed in many cities.（,（五）分词独立结构,逻辑主句（名词或代词）+ 分词短语例1We shall see how speech of a telephone channel can be conveyed as a series of amp
17、litude values, each value being represented as a sequence of eight binary digits.,例2The telecom companies are now getting involved in IPTV as they facing decreasing subscriber revenues from their voice and broadband communication. 例3The GSM system was allocated part of the 900 MHz band at the 1978 W
18、orld Administration Conference, the actual bands being 890 to 915 MHz for the uplink transmission and 935 to 960 MHz for the downlink.,例4The boy playing around most of the time, his mother was mad of him.,（六）介词短语,with (within或without)介词短语= with +名词+介词短语定语从句不定式动词短语分词短语,1介词短语作状语 例1In circuit switching
19、, direct transmission of data from source to destination can take place without any intervention on the part of the subnet. 例2Microprocessors and minicomputers are now used with power and size that was much less than previously possible. 例3A basic cellular system consists of three parts: a mobile un
20、it, a cell site, and a mobile telephone switching office with connections to link the three subsystems,2介词短语构成复合宾语 介词复合宾语=介词+名词（或宾格代词） + 分词短语不定式动词短语 例1People knew about the bus station being built. 例2I didnt know about the weather being so awful there. 例5The world wide standard for synchronous trans
21、mission system provides operators with a flexible and economic networks.,（七）虚拟语气,1虚拟现在 例1I would certainly go if I had time. 例2If a fixed dedicated end - to - end circuit were to be set up connecting the end users, then one must assign enough transmission bandwidth to the circuit.,2虚拟过去 从句：过去完成时态 ha
22、d + 过去分词 主句：过去将来完成时态 would (或might, could, must) + have + 过去分词 例1If only 4 digits per sample value had been used, the quality of transmission would drop. 例2If the video data had not been compressed, the amount of storage would have to be immense.,（八）非限定定语从句, 从句中的关系代词不是直接代表它的先行词，而是对先行词作进一步的说明。如果去掉这个从
23、句不会影响全句的主要意思。而在限定定语从句中关系代词就代表它的先行词且在从句中当主语。 一般来说，非限定定语从句的前面有一个逗号，有时这个非限定定语从句还可以修饰它前面的整个句子。 对先行词的人进行说明时用who或whom。对物进行说明时用关系代词which。 关系代词which的前面还常常带有一个介词，带有介词时的关系代词就不能在从句中当主语或宾语。,例1If the selected channel is busy, the message waits in a queue until the channel becomes free, at which time transmission
24、 begins. 例2First the message is transmitted from the host to the message processor to which it is attached. 例3The applications programs define the ways in which these resources are used to solve the computing problems of the users., 有时指示代词that 也能引导非限定性定语从句。 例：The application layer differs from the other layers in that it does not provide services to any other OSI layer, but rather, only to applications outside the OSI model.,
