1、2018/12/21,1,Scientific English Writing,EST,Fan Cong,2018/12/21,2,Relative Clause,Introduction Main Introducing Words “Preposition + which”WhichAsTwo key points,2018/12/21,3,Introduction,（一）定义一般说来 ，一个分句在另一个分句中充当了某个名词（或代词）的定语作用，这种分句就叫做定语从句。,2018/12/21,4,Introduction,（二）位置一般说来，定语从句一定要位于被修饰的词之后，也就是说只能做
2、后置定语（这与汉语的语序是不的）。,2018/12/21,5,Introduction,（三）种类 1、限制性定语从句直接影响全句确切含义的定语从句称为限制性定语从句，若把它去掉的话，原句的意思就不完整了。从形式上看，就是在定语从句与被修饰词之间没有用逗号分开。但必须注意：在被修饰词与定语从句之间偶尔会有用逗号分开的插入成分存在，既“名词，插入语等，定语从句”这一形式，不要误认为这个定语从句是非限制性的。,2018/12/21,6,Introduction,如： There is another form of energy, due to pressure, that we must tak
3、e into account. 还有一种能量形式我们必须要考虑的，它是由压力产生的。 When the switch is “open”, there is no complete path, or circuit, around which the electrons can flow. 当开关“打开”时，就不存在电子能流过的闭合通道，即电路。,2018/12/21,7,Introduction,2、非限制性定语从句只起进一步说明作用的定语从句称为非限制性定语从句。从形式上看，它与被修饰词之间由逗号分开。这种定语从句又可分为以下两类： (1)修饰主句中某个名词或代词的非限制性定语从句； (2
4、)修饰整个主句（有时修饰其一部分）的非限制性定语从句。,2018/12/21,8,Introduction,Two atoms of hydrogen, which we know as a gas, unite with one atom of oxygen, also a gas，to from a molecules of a liquid, water. 两个氢(我们知道它是一种气体)原子与一个氧（也是一种气体）原子结合在一起形成了一种液体-水的一个分子。 Determining these factors, which is essentially reversing the pro
5、cess of finding a product, is called factoring. 找出这些因子（这基本上就是将求积的过程反过来）就成为因式分解。,2018/12/21,9,Main Introducing Words,（一）关系代词 常见的关系代词有以下几个： That* Which* Whose Who As* But,2018/12/21,10,Main Introducing Words,（二）关系副词 关系副词在句中主要作状语。在科技文中常见的关系副词有以下三个。 Where* When* Why,2018/12/21,11,Main Introducing Words,
6、练习：请判断一下例句中关系代词和关系副词在从句中各作什么成分。 1. Study methods that work for other courses may not the best for physics. 适用于其它课程的学习方法对物理学这门课来说可能并不是最合适的。 2. Most of the information that we get in our everyday life is also obtained through the medium of light. 我们在日常生活中所获得的大部分的信息也是通过光这个媒介获得的。,2018/12/21,12,Main Intr
7、oducing Words,3. It is unfortunate that early cancer is painless; otherwise, cancer would not be the problem that it is. 不幸的是，早期癌症是不痛的，要不然，癌症就不会成为像现在这样严重的问题了。 4. The property of a particle that allows it to maintain a constant state of motion or rest was termed inertia by Newton. 允许质点保持运动或静止的恒定状态的这一
8、特性被牛顿成为惯性。,2018/12/21,13,Main Introducing Words,5. In this chapter we shall consider the definite integral, which every electrical engineer must know how to use to find such things as r.m.s. values, etc. 本章将讨论定积分，每一位电气工程师必须懂得如何使用定积分来求诸如均方根等这类数值。 6. We must understand the reason why this component is
9、 used here. 我们必须懂得在这里使用该部件的原理。,2018/12/21,14,“Preposition + which”,这种情况实际上就是which在定语从句中作介词宾语的情况。这种定语从句仍遵循“关系代词代哪个词，定语从句就修饰哪个词的原则”。介词的选择用该从以下三方面加以考虑。,2018/12/21,15,“Preposition + which”,1. 先行词的搭配要求 The rate at which work is done is referred to as power.做功的速率被称为功率。 In a later chapter we will see the r
10、easons for which different sources emit different types of spectrum. 在后面一章中我们将看到不同的光源发射出不同类型光谱的原因。,2018/12/21,16,“Preposition + which”,三种常见的情况总结如下：,PressureFrequency the Temperature at whichRate Height,2018/12/21,17,“Preposition + which”,MethodProcedure the Process by whichSchememeans,2018/12/21,18,
11、“Preposition + which”,careskilleaserapidity the difficulty with whichefficiencyaccuracyprecision,2018/12/21,19,“Preposition + which”,2. 从句中动词、名词或形容词的搭配要求 In all the resistances through which a current flows, electrical energy is converted into heat energy. 在电流流过的所有电阻中，电能被转换成热能。 The two elements of w
12、hich water consists are the gases oxygen and hydrogen. 构成水的两种元素是气体氢和氧。 The material of which this machine is made is iron. 这台机器是铁制成的。,2018/12/21,20,“Preposition + which”,3. 由整个句子所要表达的概念来确定。 The collector current at which the collector dissipation is a maximum is as follows. 集电极功耗为最大值时的集电极电流如下。 It is
13、 necessary to increase the range of current over which the meter is useful. 我们必须增加可利用此表的电流范围。,2018/12/21,21,Which,有时，由which引导的定语从句（一般是非限制性的）修饰的主要不是前面某个名词或代词，而多数是整个主句或主句中的一部分，这种定语从句只能分译成单独的一句，这时which一般译成this的词义，它通常有以下几种情况：,2018/12/21,22,Which,1、“which”在从句中作主语 这种情况最为常见，这时从句的谓语只能是单数第三人称形式。 The motion o
14、f a rocket does not depend on the presence of air, which was proved in 1916. 火箭的运行并不取决于空气的存在与否，这一点在 1916年就得到了证实。 The input may be connected to signal sources that have neither terminal grounded, which often proves to be convenient. 可以把输入连接到其两个断电均不接地的信号源上，这往往证明是方便的。,2018/12/21,23,Which,2、“which”在从句中作
15、介词宾语的定语,科技文中最常见的形式有：,In which case(condition, state)* 这种情况状态下At which time(instant, point)* 在这时For which reason 由于这个原因；因此,2018/12/21,24,Which,Baldness may be an expression of aging, in which case it usually begins at the crown of the head. 秃顶可能表示上了年纪了，在这种情况下，它通常是从头顶开始的。 It took Whitney two years, du
16、ring which time not a single gun was produced, to develop the machines, tools and fixtures to do the job. 研制为完成这项任务所用的各种机器、工具及夹具共花了威特尼两年的时间，在此期间一支枪也没有造出来。,2018/12/21,25,Which,3、“which”在从句中作介词宾语,常见的形式有：,From which 由此After which 在此之后；然后Because of which 因此，由于这个原因As a result of which 因此，由于这个原因,2018/12/2
17、1,26,We equate the mole ratio to the atom ratio, from which the simplest formula follows directly. 我们使克分子比与原子比相等，由此直接得到了最简分子式。 Some materials have a very high resistance, because of which they can be used as insulators to prevent the leakage of current. 有些物质的电阻率很高，因此可以用作绝缘体来防止漏电。,Which,2018/12/21,27
18、,As,1、as引导的修饰整个主句的非限制性定语从句 As this title indicates, this chapter will deal primarily with series of complex numbers. 如标题所示，本章主要讨论复数的级数。 Transistors are small and efficient, as is well known to us. 晶体管体积小、效率高，这是我们大家所熟知的。 This material is elastic, as is shown in Fig.2. 如图2所示，这种材料是弹性材料。,2018/12/21,28,A
19、s,1、as引导的修饰整个主句的非限制性定语从句 表示“顾名思义”的句型总结如下：,ShowsIndicates As the/its/their name ImpliesSuggests The decibel(dB), as its names shows, is just one-tenth of a bel. 顾名思义，分贝（dB）就是0.1贝尔。,2018/12/21,29,As,2、as引导的修饰某个名词的限制性定语从句（常与 such和the same连用） This force produces the same effect as is produced by the sim
20、ultaneous action of the given forces. 这个力产生的效应与给定的几个力同时作用产生的效应相同。 Such meters as we use to measure current are called ammeters. 我们用来测量电流的这类仪表称为电流表。,2018/12/21,30,As,3、一种特殊的as结构 （1）形式过去分词As + 介词短语副词,2018/12/21,31,As,（2）功能 主要作状语和定语，有时可作表语 As pointed out in the previous chapter, forces are not transmit
21、ted only by “direct contact”. 正如前一节所指出的，力不仅仅是靠直接的解出来传递的。 As with the circular functions, we have the reciprocals of the above three hyperbolic functions. 如同圆函数的情况，我们可以获得上述三种双曲线的倒数。,2018/12/21,32,Two key points,（一）只能使用that而不能使用which的几种情况 1、先行词为all, everything, nothing, something, anything, little等不定代
22、词时； Anything that is hot radiates heat. 任何热的东西均辐射热量。 All that one should do is to adjust the resistance. 人们所应做的就是调整一下电阻。,2018/12/21,33,Two key points,（一）只能使用that而不能使用which的几种情况 2、先行词被序数词或only，no，very等词修饰时； The first thing that will be done is to measure the voltage across this component. 要做的第一件事是测出该
23、元件两端的电压。 The only measure that one can take in this case is to connect a capacitor across R. 在这种情况下，我们所能采取的唯一措施就是在R两端并接一个电容器。,2018/12/21,34,Two key points,（一）只能使用that而不能使用which的几种情况 3、先行词被形容词最高级修饰时； Computers are the most efficient assistants that man has ever had. 计算机是人类所曾有过的效率最高的助手。 In practice, t
24、he best that the analog computer can achieve is an accuracy of about 1 part in 10,000. 实际上，模拟计算机所能达到的最高精度大约为万分之一。,2018/12/21,35,Two key points,（二）关系代词可省略的场合 1、关系代词在句中作及物动词的宾语时可省。 These are the kinds of grammatical structures and sentence patterns scientists prefer. 这些是科学家们喜欢采用的语法结构和句型。 The amount of
25、 gravitational pull a body produces depends on the amount of material in it. 一个物体所产生的万有引力的大小取决于它所含物质的多少。,2018/12/21,36,Two key points,（二）关系代词可省略的场合 2、在the way, the distance, the direction, the reason, the time, the number of time/units, the amount等词后可以省略关系副词或“介词+ which”。 Work is the product of the f
26、orce and the distance a body moves. 功等于力与物体运动距离的乘积。 (在the distance 之后省略了through which) The damped oscillation depends on the time the switch is closed. 阻尼振荡取决于开关闭合的时间。 (在the time之后省略了when或at which),2018/12/21,37,Two key points,（二）关系代词可省略的场合 3、当关系代词which在从句中作单个介词（而不是短语介词）的介词宾语时，此介词短语在从句中作状语时可以省略，其条件是
27、一定要把介词置于从句末尾。 Power is the rate work is done at. 功率是做功的速率。 The resistance of a conductor also depends on the substance it is made of. 导体的电阻大小还取决于制成导体的物质。 These are the metals we are most familiar with. 这些是我们最熟悉的金属。,2018/12/21,38,Two key points,（二）关系代词可省略的场合 4、关系代词在从句中作表语时可以省略。 Communicating via sate
28、llite is no longer the novelty it once was. 卫星通讯已经不再是件新奇事了。 The sum of the squares of the deviation of all points from the best line is the least it can be. 各点与最佳线偏离的平方之和是所能获得的最小值。,2018/12/21,39,Two key points,（二）关系代词可省略的场合 5、关系代词在从句中作there be句型的主语时可以省略。 The thermometer does not tell us about the am
29、ount of heat there is in the liquids. 温度计并不能告诉我们液体中所存在的热量。 The antenna picks up any signals there may be about. 天线能接收在周围可能存在的任何信号。,2018/12/21,40,Two key points,（二）关系代词可省略的场合 6、定语从句修饰there/here be句型的主语时，作主语的关系代词可以省略。 There is something worries digital designers. 有件事使数字电路设计师们感到烦恼。 Here are some ideas will help you to realize how small atoms are. 下面一些概念将有助于你了解原子有多小。,
