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1、三,名词性从句和副词性从句 在科技英语中，为完善、准确地表达复杂的内容，常使用复合句，因为这些内容用简单句是不能表达的。如果一个句子中有一个或一个以上的成分，不是由词汇或短语来担任，而是由一个完整的句子来担任，构成一个主体句子代一个或一些从属句子成分的复合结构，这种复合结构就叫主从复合句，其中主体部分叫主句，从属部分则叫从句。在句子中起名词作用的从句叫做名词从句，名词从句可以作主语、宾语、表语和同位语，因而分别叫做主语从句、宾语从句、表语从句和同位语从句；在句中起形容词作用的从句叫做定语从句，起副词作用的从句叫做状语从句。由于是一个十分重要的、出现极多的成分，我们将在后面加以专门的介绍，这里先
2、简要介绍名词性从句和状语从句。,I.名词性从句:；可作主语,表语,宾语,同位语.1.主语从句一个句子中，如果它的主语是由一个句子来担任，则担任主语的这个句子就叫做主语从句，如：That electricity is a form of energy is known to all of us.(电是能的一种形式是人所共知的)句中的That.energy就是主语从句，在句中担任主语。从结构上看，各种从句都有其引导词起标志、连接或在从句中担任某一成分的作用。连词:一般起标志连接的作用,并在从句中担任某种成分.。引导主语从句的词有三类：.主从连词:,如that,whether,，that 引导从句时
3、无词义，起标志和连接的作用，whether 引导主语从句时，则有词义“是否”，如：Whether the materials could stand the test is still a problem.)这些材料能否试验合格还是个问题）.连接副词:how,when,where,why，它们在引导主语从句时，都有词义，作用有三：标志，连接并在从句担任状语，如：Why metals can conduct electricity is an interesting problem.(金属为什么能导电是一个有趣的问题)Where we shall go for practice has njot
4、 been decided.(我们去何处实习尚未决定)How these elements are combined is clearly known.（这些元素是如何结合的是人们清楚了解的）,.连接代词:who,whom,whose,what,which,在句中担任主语,宾语,表语或定语.What he said is quite important to you.（宾语）Who knows him will believe him.（主语What has been said above is very important.What a motor does is to change ele
5、ctrical energy into mechanical driving power.(电动机所起的作用是将电能转变成机械驱动能)Which process is more economical can be easily seen.(哪一个过程更经济很容易看出)在应用主语从句时，为避免句子头重脚轻，主谓不平衡，常使用“it+谓语+主语从句”这样的结构，其中it 是形式主语，主语从句则是实际主语，如：It is obvious that electronic computers are playing an important role in the field of science an
6、d technology.这种类型的主语从句:在科技英语中常常可以见到.：.It+不及物动词(follows,turns out.)+that,表示”可以推断,原来是.,结果是.”:It follows that not all substances are good conductors of electricity.由此可见,并非一切物质都是良导体.,It turns out that megnetism is as fundamental to fabric of the universe as mass,electric charge and gravitation.原来,磁同质量,电
7、荷和万有引力等一样,是宇宙结构最基本的东西.”It+(seems,appears,to be true,evident,the fact)+that”:It is true that silver is the best conductor of all metals.,2.表语从句:一个句子的表语若是由一个句子来担任，那么担任表语的这个句子就叫做表语从句。如：The problem is why the plane can fly.(问题是飞机为什么会飞)引导表语从句的常用连词与主语从句的连词基本相同。The followings is what the radar is and how i
8、t works.以下是:什么是雷达以及雷达是怎样工作的.,3.宾语从句:：一个句子中的宾语从句若是由一个句子来担任，则担任表语的这个句子就叫做宾语从句。引导宾语从句的连词与主语从句的连词基本相同。Ohms law tells us that electric current is equal to voltage divided by resistance.To understand what atomic energy is,we must first have a correct knowledge of the atom.They need to know if the material
9、 is heat-resistant.Rome is a city famous for what it was rather than what it is.如果宾语代有宾语补足语，则通常是把宾语从句移到句末，而以先行代词it 作形式宾语，置于宾语补足语之前，People have proved it to be true that the heat we get from coal and oil comes originally from the sun.You can easily show it to be true that oxygen is very active.(你可以很容
10、易证实：氧是非常活泼的)We all consider it of great importance that we should combine theory with practice.(我们大家都认为，理论联系实际是非常重要的),II.副词性从句:起副词作用，在主句中担任各种状语，表示时间、地点、方式、条件、目的、原因、结果比较、让步等；1时间状语从句：时间状语从句可以位于主句之前、之后或主谓语之间，位于主句之前时，往往有一逗号与主语隔开，若位于主句的主谓语之间时，则前后都有逗号与主句其它成分隔开。可以引导时间状语从句的有 when,whenver,while,as,before,aft
11、er,since,till,until,as soon as,no sooner.than,each time,every time:等，如When：A.C flows through a coil,an alternating magnetic field is generated around the coil.(当交流电流通过线圈时，在线圈周围就产生一交变磁场)We should go on testing until we get the correct result.The computer can also keep millions of scientific facts and
12、“remember”where each one is,and provide any particular information any time the scientific workers need it.（电子计算机还可保存大量科学数据,”记住”每一个数据在哪儿,并且每当科学工作者需要特殊资料时,它还可以提供任何这种资料.）,.地点:状语从句：地点:状语从句可以于主句之前或之后，位于主句之前时，一般都有逗号与主句隔开，可以引导地点状语从句的有where和wherever,如：Where the watt is too small a unit,we may use the kilow
13、att.(在用瓦特作单位嫌小的地方，可用千瓦)Wherever there is plenty of sun and rain,the fields are green.,3原因:状语从句：原因:状语从句可位于主句之前或之后，当位于主句之前时一般有逗号与主句隔开。可以引导原因状语从句的有 because,as,since,now that,considering that 等，如：Some materials are are called good conductors because electricity goes through them well.Water,as it occurs
14、in nature,is never very pure.Since electricity is a kind of energy,it can be changed into other forms of energy.(既然电是一种能，它就可以转换成为其它形式的能)Because 与 because of 的区别：前者是连词,后跟句子;后者为复合介词,后面只能跟名词:Air can not be an element because an element can not be separated.Alloys are important because of usefulness in
15、industry.,条件状语从句:条件状语从句一般主句之前或之后。可以引导条件状语从句的有 if,unless,in case,so long as,as long as,provided(that),on condition that 等，如：Electric current does not flow unless there is a potential difference between the two ends of a conductor.As far as we know,not all of us realize the importance of this step.Iro
16、n rusts if it is placed in the open air.(铁如果放在露天就会生锈)We can know the voltage provided that we know both the current and resistance.,5.让步状语从句：表示主句中的动作或状态是在和从句的动作或状态矛盾的情况下进行和实现的。让步状语从句可以位于主句之前或之后，或主谓语之间，可以引导让步状语从句的有though,although,as,while,however,even if,even though,whether.or,no matter how,(who,what
17、,which,while,when,where)等，如：However remarkable an electronic computer is,it cannot replace man.（不管电子计算机怎样好，也不能代替人。）Every substance,no matter what it is,is made up of atoms.（任何物质，不管它是什么，都由原子组成。）All metals will melt though some require greater heat than others.No matter how complicated its appearance
18、is,every machine may be broken down into smaller and smaller assembles.(不管机器外形多么复杂，都可以把它分解成越来越小的装配件),6目的状语从句：表示主句动作或状态产生的目的或动机。除由in order that 引导的可位于主句之前外，其余的目的状语从句均位于主句之后。常用的连词：in order that.,为了，以便 so that.为了，以便 lest 以免如：In order that work can be done,in scientific,sense,a force must move an object
19、 through some distance.(从科学意义上进，为了做功，力必须推动物体通过一定的距离)The resistance must be reduced so that we can have a stronger current.,7结果状语从句：结果状语从句位于主句之后，说明主句中动作产生的结果，但通常并不直接说明动词，而是说明形容词或副词。可引导结果状语从句的有so.that,such.that,such that，suchthat等，如：The temperatures in the turbine are such that special materials have
20、to be used.(涡轮机中的温度很高，因此必须使用特殊材料)A motor can be made in such a small size that it may be easily placed anywhere.（电动机可以造得很小，便于到处安放）The climate is very hot and dry that much evaporation takes place.气候既非常炎热又很干燥，因而发生大量的蒸发。So exact were his observations that it was possible for him to predict the discove
21、ry of a number of unknown elements and to describe their properties.他的观察极为精细，因而他可以预言未来会发现多种未知的元素，并且能描述它们的特性。,8.方式状语从句：除由just as 和as.so引导时，可以位于主句之前外，方式状语从句均位于主句之后，表示主句中动作或状态进行或发生的方式方法。可以引导方式状语从句的有as,just asas,just asso,as if,等,如：Even the most able computer,can only act as people enable them to act.(即
22、使最好的计算机也只能按人所赋予它的能力去做)As the steam engine is the most important invention in the 18th century,so the electronic computer is the most important invention in the 20th century.(电子计算机是二十世纪最重要的发明，就像蒸汽机是十八世纪最重要的发明一样,Exercise把下列英语译成汉语：Whether an electric current can be produced by magnetism is a question s
23、olved many years ago.It is obvious that electrionic computer are plying an important role in the field of science and technology.The question is when the instrument will be installed.The fact is that not all substances are good conductor of electricity.Almost everyone knows who invented the compass.
24、Through power lines electric power is transmitted to where it is needed.The atmosphere gets thinner and thinner as the altitude.Increase.Before he operated the machine,he had it well oiled.He knew nothing about the blue print until I told him.The higher the temperature of the the air is,the more water vapour it can a,
