现在分词作状语详解

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1、【精品文档】如有侵权，请联系网站删除，仅供学习与交流现在分词作状语详解.精品文档.教学目标：讲解现在分词作状语及区分不定式、现在分词作状语的异同重点难点：1.现在分词和不定式作状语时，其逻辑主语一般应与句子的主语保持一致。2.分词作状语时，要看它同句子主语之间的关系，以确定是现在分词还是过去分词。3.注意非谓语动词与句子谓语动词的时间关系，以确定分词的时态形式4、弄清非谓语动词与其逻辑主语的关系，以确定非谓语动词的语态形式.5. 连词+分词形式（分词作状语的省略问题）6.不定式作结果状语和现在分词作结果状语的区别。7. 现在分词的独立主格结构和评价性状语Step 1 lead in 朗读下面一

2、首唐诗，找出其中的现在分词形式Thinking in the Silent Night 静夜思Before my bed there is bright moonlight 床前明月光So that it seems that frost on the ground. 疑是地上霜Lifting my head, I watch the bright moonlight. 举头望明月Lowering my head, I dream that Im home. 低头思故乡Step2 现在分词作状语的意义动词的现在分词作状语，修饰动词，相当于状语从句，在句中表示时间、原因、结果、条件、让步、行为方

3、式或伴随情况及独立成分等，作时间、原因、条件、让步状语时多位于句首；作结果、伴随情况状语时常位于句末。一. -ing分词短语作时间状语，代替一个时间状语从句(引导词有when ,while )温馨提示：1现在分词所表示的动作与主句的动作一般是同时发生，有时可由连词when, while引出。 2现在分词所表示的动作一发生，主句的动作就立即发生时。 如：When she saw those pictures，she remembered her childhood.=Seeing those pictures, she remembered her childhood. 看到那些画，她想起了自己

4、的童年。As soon as he heard the good news, he jumped with joy.=（0n）Hearing the good news, he jumped with joy.他一听到这个好消息，就高兴地跳起来。二-ing分词短语作原因状语，相当于一个原因状语从句。(引导词有because ,as ,since)如：As he was ill, he didnt go to school yesterday=Being ill, he didnt go to school yesterday. 由于生病，他昨天没有上学。三-ing分词也可作条件状语和让步状语，

5、相当于一个条件状语从句。(引导词有if,unless,once) If you work hard, you will succeed.=Working hard, you will succeed. 如果你勤奋一点，你就会成功。If you turn to the left, you will find the path leading to the school.=Turning to the left, you will find the path leading to the school.如果你向左转，你就会找到到学校取得路。四表示让步，相当于让步状语从句（引导词有although,

6、though,even if ,even though）Although they knew all this，they made me pay for the damage.= Knowing all this, they made me pay for the damage. 尽管知道了一切情况，他们还是要我赔偿损失。五现在分词可以做方式状语、伴随状语，表示行为方式、伴随情况或补充说明，是主语的另一个、较次要的动作，相当于一个由and引导的并列结构。She came into the house,and carried a lot of books.=She came into the h

7、ouse, carrying a lot of books. 她捧着许多书走进了房间。He lay on the grass, and stared at the sky for a long time.=He lay on the grass, staring at the sky for a long time. 他躺在草地上，长时间地望着天空。温馨提示：伴随状语出现的条件是由一个主语发出两个动作或同一个主语处于两种状态，或同一个主语发出一个动作时又伴随有某一种状态。六现在分词表示主句的动作所带来的必然结果，相当于一个并列谓语His father died, and left him a

8、lot of money.=His father died, leaving him a lot of money. 他父亲死了，留给他许多钱。 She was so angry that she threw the toy on the ground, and broke it into pieces.=She was so angry that she threw the toy on the ground, breaking it into pieces. 她非常生气，把玩具扔在地上，摔成了碎片。Step 2考点解读分词作状语应注意的问题A. 分词作状语的首要条件是分词的逻辑主语是句子的

9、主语。动词的分词形式作状语时，其逻辑主语一般应与句子的主语保持一致。Entering the classroom, I found nobody in it. 走进教室，我发现里面没人。（entering的逻辑主语是I，相当于when I entered the classroom, I found nobody in it.） 如分词表示的动作不是句中主语发出或承受的，那就是误用。课堂巩固练习：判断下列句子正误1. 从窗户看出去，我们看见一个漂亮的花园。 a. Looking out through the window, the garden was beautiful.b. Lookin

10、g out through the window, we saw a beautiful garden.2. 我看着晚报的时候，一只狗开始叫起来。 a. Reading the evening newspaper, a dog started barking. b. I was reading the evening newspaper when a dog started barking.3. 听到这个消息，我的眼泪忍不住流下来。a. Hearing the news, tears ran down her face. b. Hearing the news, she cried out s

11、adly.4.等公汽的时候，一块砖头砸在我的头上。a. waiting for the bus , a brick fell on my head.b.waiting for the bus ,I was hit by a brick on the head.5.打开窗户，一只蝴蝶飞进来了。a. Opening the window, a butterfly flew into my room.b. Opening the window, I saw a butterfly flying into my room.6.如果你努力学习，你的梦想一定会实现。a.Working hard with

12、a strong will, your dream will certainly come trueb.Working hard with a strong will, youll certainly make your dream come trueB. 独立结构分词的逻辑主语如不能和句子中的主语保持一致，该-ing形式必须有自己的逻辑主语，通常有名词或代词来担任,成为独立主格结构，独立结构可以表示伴随动作或情况, 表示时间、原因、条件等。但要注意主格词和主句的主语不能表示同一概念，主格词和分词的动作是主谓关系结构是：形式：主格词+doing主格词+being +adjthere being

13、 +n,辨别正误因为天气好，我们下周将举行运动会。a. Being fine, we will have the sports meeting next week. b. It being fine, we will have the sports meeting next week. 练习：把下面句子改成独立主格形式1.If the weather permits, well go out on an outing. =Weather permitting, well go out on an outing. 天气许可的话，我们就去郊游。2. Because it is Sunday, we

14、 neednt go to school.=It being Sunday, we neednt go to school. 因为是星期天，我们不需要上学。3.Since there was no buses,we had to walk home .=There being no bus ,we had to walk home .因为没有车，我们不得不走回家。4.As the boy led the way, we had no trouble finding the village. The boy leading the way, we had no trouble finding t

15、he village.因为有这个男孩带路，我们毫不费力地找到了这个村子。小结：当主从句主语不一致时，分词和逻辑主语构成.独立主格.例如：Time permitting, the football match will be played on Friday. 天气允许的话，足球赛将在周五举行。（permitting的逻辑主语是time，而不是the football match）The professor being absent ,the lecture had to be put off.教授缺席了，演讲不得不推迟。The meeting being over, they all left

16、 the meeting room.会议结束了，他们都离开了会议室。课堂巩固练习1. _,I will go over all these lessons before the exam.A. If time will permit B. Time permits C. Time permitted D. Time permitting 2. I carefully poured the liquid into the water , my classmates _anxiously beside me to see what would happen.A. stood B. standing

17、 C. to stood D. were standing 注意：有一种习惯表达作评价性状语，表示说话人的态度，观点和看法等，就不必考虑与主句的主语之间的逻辑关系，因为说话者就是分词的逻辑主语，它们的逻辑主语可以和句子的主语不一致必背： 分词或分词短语作独立成份（作状语或插入语） Generally / Frankly / Roughly speaking一般说来/坦白说/粗略地说， judging by/from从来看，依据来判断，seeing that 考虑到，allowing for 鉴于，顾及到， talking/speaking of谈及，Taking into considerat

18、ion把考虑在内其中的considering 鉴于/考虑到，following继之后，concerning关于，regarding关于，respecting关于，owing to 由于就是介词）例如：Generally speaking, boys are more interested in science than girls.一般说来，男孩比女孩对科学更感兴趣。 Judging from his accent, he must come from Canada. 从他的口音看，他一定来自加拿大。 Supposing it rains ，what will you do 假使下雨，你会怎么

19、办呢？Talking of cleaning, its about time you cleaned the classroom.谈到打扫卫生，该你打扫教室了。C非谓语作状语时，要看它同句子主语之间的关系。和句子主语构成主动关系时，用现在分词作状语，和句子主语构成被动关系时，用过去分词作状语对比练习：a._from the top of the building, we saw the house like a match box.b._from the top of the building, the house looks like a match box.A. Seen B. Seein

20、g C. To see D.See 辨别正误：1.因为漆成了白色，房子看起来更美了。a. Painting white , the house looks more beautiful.b. Painted white ,the house looks more beautiful.2. 受到他的话的鼓励，我开始认真学习。a.Encouraging by her words, I got down to studying hard.b. Encouraged by her words, I got down to studying hard课堂练习1.The secretary worked

21、all night long, _ a long speech for the president.A. to prepare B. preparing C. prepared D. was preparing2. _ to hospital in time, the wounded soldiers were saved at last.A. Taken B. Taking C. Having taken D. Being taken比较下列句子3. 1）._one of the leading poets in America today,he has also written a num

22、ber of books and plays.2）._the price ,the car is worth buying .3）.All things _,the plan trip will have to be called off.A. be considered B. considered C. considering D. having considered4.1） the first place in the maths examination, liufang got another first in the English contest.2）.The professor e

23、ntered the lecture hall , by many students.3）.Many students entered the lecture hall ,_the professor.A. following B. followed C. to follow D. being followedD. 分词或分词短语作状语时，前面可以加上连词，但是分词短语和句子之间不能用并列连词(如but，and,so ,or)，因为并列连词接的是两个并列成分，而分词短语只是全句的一个状语部分，分词和主句之间可用逗号。辨别正误：1.尽管被告知了很多次，但是他仍然不能理解。a.Having bee

24、n told many times, but he still couldnt understand it.b.He was told many times, but he still couldnt understand it. c. Having been told many times, he still couldnt understand it.d. Though he had been told many times, he still couldnt understand it.e. Though he had been told many times, but he still

25、 couldnt understand it.2.因为生病了，所以他被立刻送到医院去。a.Being ill ,so he had to be sent to the hospital at once.b.He was ill ,so he had to be sent to the hospital at once.c. Being ill ,he he had to be sent to the hospital at once.E.不定式和现在分词作结果状语的区别不定式作结果状语表示意料之外的结果，常和only 连用现在分词作结果状语表示主句的动作所带来的必然结果，常何thus 连用温馨

26、提示：要掌握好现在分词短语作结果状语的用法，须注意以下几点： a. 句子的主谓部分与分词之间含有逻辑上的因果关系， b. 这种作结果状语的现在分词短语的逻辑主语可以是句子的主语，也可以前边的整个句子.例如;The bus was hold up by the snow, thus causing the delay.公汽被大雪阻住了，结果引起延误。His car was caught in the traffic jam ,causing him to be late.他的车陷入了交通堵塞，结果引起他迟到了。He dropped a plate on the ground, breaking

27、it into pieces.他把盘子掉在地上，结果摔碎了。At the age of three his parents died, leaving him an orphan.三岁的时候他父母去世了，留下他一个孤儿。He was caught in the rain, thus making himself catch cold. 他撞上了雨，结果使他感冒了。.He didn t come today, making it necessary for us to find someone to do his work.他今天没来，因而我们必须找人干他的工作。对比：不定式作结果状语He ma

28、de a long speech, only to show his ignorance。他发表了长篇大论，结果显示出他的无知。He lifted up a stone only to drop it on his own feet.他搬起石头砸自己的脚。He went to the seaside only to be drowned。他到海边去结果淹死了。Yesterday a street -beggar bought a lottery ticket , to make him a millionaire overnight .昨天一个街头乞丐无意买了一张彩票结果使他一夜间成了一个百万

29、富翁。巩固练习1)The storm left , a lot of damage to this area .(2005年全国卷) Acaused Bto have caused Cto cause Dhaving caused2)European football is played in 80 countries , _ it the most popular sport in the world . (NMET 1998)A. making B. makes C. make D. to makeStep3 分词的形式A.分词的一般式和完成式温馨提示：1：现在分词所表示的动作与主句的动作

30、一般是同时发生， 现在分词所表示的动作一发生，主句的动作就立即发生时,两个动作几乎同时发生时，用现在分词的一般式。2.分词的的动作发生在谓语动词表示的动作之前，用现在分词的完成时作状语。把下列状语从句改成分词形式：1.因为他晚饭吃得太多，他睡不着。As he had eaten too much for supper, he couldnt go to sleep.=Having eaten too much for supper, he couldnt go to sleep.2. 他把窗户关上后就回家了。After he closed the windows, he went home.。

31、=Having closed the windows, he went home。3.因为听到了奇怪的声音，他走出房间看看。After he heard a strong sound, he went out of the room for a look.= Hearing a strange sound, he went out of 3. Because he had been to the Great Wall many times, he didnt go last week.=Having been to the Great Wall many times, he didnt go

32、last week. 因为他已经去过长城许多次，上周他就没去。例如：They went to the park, singing and talking. 他们说说笑笑地向公园走去。Hearing the news ,he couldnt help laughing .听到这个消息，他禁不住笑了。Having finished his homework, he went to bed.做完了作业，他就去睡觉了。Having waited for half an hour,I became a little impatient.等了半小时，我有点不耐烦了。Having turned off th

33、e TV, he began to go over his lessons.把电视关掉后，他开始复习功课。Having put up the tent,they started to cook supper.搭好帐篷后，他们开始做晚饭。小结：是否用分词的完成式要看动词是否存在明显的先后关系。二现在分词的被动式被动一般式 being done 一般做后置定语，表示正在被做的动作被动完成式 having been done把下列句子改成分词形式1.这本书在被翻译成多种语言后在全世界有名了。This book become well known all over the world after it

34、 had been translated into many different languages.=Having been translated into many different languages, this book become well known all over the world .2. This is one of the new supermarkets in our city,which is being built at present.=This is one of the new supermarkets being built at present. in

35、 our city. 这是我们城市正在建的超市之一。3.Though he had been defeated many times , he didnt lose heart.=Having been defeated many times , he didnt lose heart.尽管被打败多次，但是他没有气馁。例如：The problem being discussed is very important. 正在被讨论的问题很重要。Having been told many times, he was able to operate the machine.被告诉了很多遍，他能够操作机

36、器了。Having been warned several times , the naughty boy made the same mistake. 被警告过多次，这个淘气的孩子又犯了同一个错误。Having been criticized by the teacher, he gave up smoking.被老师批评后，他戒烟了。三分词的否定形式分词的否定式，由not/never+分词构成，即not doing ,not having done ,no having been done 把下列句子改成分词形式1. 因为他没有收到回音，所以决定再写一封信。As he didnt rece

37、ive a reply, he decided to write another letter.=Not having received a reply, he decided to write another letter.2.因为我不知道他的地址，所以不能和他取得联系。As we didnt know his address, we couldnt get in touch with her.=Not knowing his phone number, we couldnt get in touch with her.例如：Not having heard the news. I wrot

38、e to him again. 没有听到这个消息，我又给他写了信。Not knowing how to work out the maths problem, I went to the teacher for help.不知道怎么解决这个数学题，我向老师求助。Not recognized his voice, she refused to give the person her address.没有听出他的声音，他拒绝把她的地址给这个人。Not having received an answer, I decided to pay a visit to him.没有收到一个答复，我决定去拜访

39、他。E.现在分词的省略形式有时，为了使非谓语动词短语与主句的逻辑关系更清楚，可在非谓语动词前加连词。时间关系的连接短语有时还可以由连接词while或when引导。温馨提示：当状语从句用省略的时候，一般要具备两个条件：状语从句的主语和主句的主语要一致且状语从句的谓语含有be。当具备这两个条件后，状语从句若用省略时，一般同时省略两部分：状语从句的主语；状语从句谓语中的be。While (he was) playing football, he had his leg broken.当他踢足球时，腿折了。When （he was ）asked why he was late ,the boy tol

40、d a lie.当被问及他为什么迟到的时候，这个男孩撒了谎。While lying in bed, he listened to some music.他躺在床上听音乐。He looked through a newspaper while having breakfast.吃早饭时他翻阅报纸。When playing the piano ,she got excited.在弹钢琴时，她变得很激动。Be careful when crossing the street.过马路时要小心。Step4非谓语作状语的解题总方法与思路：1.先看四个答案：如果四个答案分别为动词原形、不定式、现在分词、过去

41、分词等情况，那么这个题多半是非谓语动词题。2.看符号：中间有个逗号，末尾有个句号。3.看有没有连接词（引导词）。如果用逗号隔开的两个部分都没有连接词的话，一部分是句子时，那么另一部分就一定是非句子，而非句子里的动词就是非谓语动词。在“句子，非句子”结构中，非句子部分用非谓语：如： The teacher devoted his life to his career, _ most of his students successful in study.A. make B. to make C. making D. made 在“非句子，句子”结构中，非句子部分用非谓语： _with child

42、ren, I know what is needed most.A. Working B. Having worked C. Worked D. To work 4.定语态：如果本句的主语（或动词自带的逻辑主语）与它是逻辑上的主谓关系，那么答案一般用Ving形式；如果本句的主语（或动词自带的逻辑主语）与它是逻辑上的动宾关系（被动关系），那么答案一般用Ved形式。5.定时态：如果非谓语的动作比谓语先（或先很久）发生，有明显的先后顺序，那么非谓语动词要用完成式，否则我们要用非谓语的一般式解题原则（高考真题分析）原则一、两个句子必须要用连词连接，如果没有连词连接，则需要用非谓语动词，有连接词就要用句

43、子。例1. _ many times, but he still couldnt understand it.A. Having been told B. Having told C. He had been told D. Though he had been told例2_ many times, he still couldnt understand it.A. Having been told B. Having told C. He had been told D. Though he had told解析：例1中有连词but连接，表明前后都是句子，所以答案为C。 例2中后面是一个句

44、子，而且没有连词，所以前面不是句子，应该用非谓语动词，根据句意此处为被动，所以答案为A。温馨提示：在“句子, and/or +句子” 的并列句结构中，可能会考查“以动词原形开头”的祈使句，四个答案表面上象非谓语，其实考查的是谓语。1） _hard and you will succeed in the exam.2）)._hard or you will fail in the exam.A. Study B. To study C. Studying D. Studied 3）_some of this juice, perhaps youll like itA.Trying B, Try

45、C, To try D. Have tried4）_at the door before entering please.A.Knock B. Knocking C. To knock D. Kocked原则二、不及物动词无-ed形式的非谓语动词，及物动词有宾语时用-ing形式，无宾语时用-ed形式。Seated at the back of the classroom, he kept still.坐在教室后面，他一动不动。There are three reading rooms in our new library, seating about four hundred students

46、 in all.在我们新图书馆有三个阅览室，能容纳400个学生就坐。Seating himself/Seated (Sitting) in the room, he is absorbed in reading.坐在房间里，他专心看书。例3. _ in the mountains for a week, the two students were finally saved by the local police.A. Having lost B. Lost C. Being lost D. Losing 解析：lose为及物动词，现在后面没有宾语，所以用-ed形式，答案为B。原则三、bein

47、g done 表示“正在被”，一般不作状语，只作定语。非谓语动词的完成时形式to have done或having done强调该动作发生在句子谓语动词之前。例4. （08重庆卷）_ to reach them on the phone, we sent an email instead.A. Fail B. Failed C. To fail D. Having failed 解析：根据句意“我们没有打通电话，就给他们发了个邮件”，没有打通电话应该发生在发邮件之前，所以用having done，答案为D。原则四.非谓语动词作状语，其逻辑主语必须和句子主语保持一致，和句子主语构成主谓关系时用-

48、ing形式，构成动宾关系是用-ed形式。其逻辑主语和句子主语不一致时，要在非谓语动词前加逻辑主语，构成独立主格结构。例5（09北京卷） _ twice, the postman refused to deliver our letters unless we changed our dog. A. Being bitten B. Bitten C. Having bitten D. To be bitten解析：本题考查非谓语动词作状语，其逻辑主语应和句子主语the postman一致，the postman应该是被咬，所以答案为B。例6 .（08安徽卷）_ in the fields on

49、a March afternoon, he could feel the warmth of spring. A. To walk. B. Walking C. Walked D. Having walked解析：本题考查非谓语动词作状语，其逻辑主语应和句子主语he一致, he 和walk应该是主动关系，所以答案为B。例7 . （04全国II） While watching television, _. A. the doorbell rangB. the doorbell rings C. we heard the doorbell ringD. we heard the doorbell

50、rings 解析：根据“非谓语动词作状语，其逻辑主语必须和句子主语保持一致”的原则，watching的逻辑主语应和后面句子主语一致，所以句子主语应为“we”，答案为C。例8. 2007 重庆卷 The girl in the snapshot was smiling sweetly, her long hair _ in the breeze A. was flowing B. flowing C. flowed D. having flowed 解析：本题没有连词，所以后面应用非谓语动词，her long hair是非谓语动词的逻辑主语，和非谓语动词构成独立主格结构。所以答案为B。原则五、不

51、定式做状语一般有两种：目的状语和出乎意料的结果状语（表示顺其自然的结果用-ing形式）。例9.（04福建） The news reporters hurried to the airport, only _ the film stars had left.A. to tellB. to be toldC. tellingD. told解析：本句句意为“记者们匆匆赶到机场，却被告知明星们已经走了”，表出乎意料的结果常常用only to do，所以答案为B。例10. The glass doors have taken the place of the wooden ones at the ent

52、rance, _ in the natural light during the day. 2007 天津卷A. to let B. letting C. let D. having let解析：本题句意为“玻璃门替换了木头门，自然光就进来了”，自然光进来时顺其自然的结果，所以用doing, 答案为B。例11 . His parents were killed in the accident,(thus )_ him an orphan.A. leave B. leaving C. left D. to leave 解析：他父母出了事故，他变成了孤儿就是意料之中在事情了，用现在分词表结果状语。

53、 例 12. I hurried to school, only _ that it was Sunday. A. find B. finding C. found D. to find解析：发现是星期天是我匆忙赶到学校意料之外的结果，说明我忘记了，如果我知道是星期天就不可能还匆忙地赶到学校了。用不定式表意料之外的的结果。注意：表示“为了”，常用不定式作状语，这时，状语动词动作发生时间与句子谓语动作时间相比，是将来，例如：例13.（09辽宁卷） , you need to give all you have and try your best.A Being a winner B To be

54、a winner C Be a winner D Having been a winner解析：根据句意“要想成为获胜者，你要付出所有，尽最大努力”，此处表目的，所以答案为B。对比：He sent me an e-mail, _ to get further information.A. hoped B. hoping C. to hope D. hope答案为B. 现在分词hoping表示与send me an e-mail同时发生的动作。一些考生认为应该填不定式作目的状语。不定式作目的状语时，句子的正确形式是：He sent me an e-mail to get further info

55、rmation.不需要hope一词，如果要选择“hoped”时，句子的正确形式是：He sent me an e-mail and hoped to get further information。“hope”和“sent”作并列谓语。比较：1）.He worked deep into the night, preparing(prepare) a speech for the president. 2）. I got up very early this morning to prepare breakfast for my family.原则六、 现在分词的否定原则是在ing前加not，有

56、not doing, not having done, not having been done几种形式。例14.（08浙江卷）_that he was in great danger, Eric walked deeper into the forest.A. Not realized B. Not to realize C. Not realizing D. Not to have realized解析： 本题考查doing的否定形式not doing，答案为 C。原则七：主动表示被动意义，要用现在分词作状语1. 表示感觉的系动词用主动形式表示被动意义，如feel(摸起来) ,sound（

57、听起来） ,look（看起来）,taste（味道尝起来）,smell（闻起来）2. 不是强调被动动作，而是表示动作的性质和特征的用法，后面带有well ,easily,smoothly 等。例如;The book sells well.The door opens easily.例15._ tired and weak, the woman should have a day off to see a doctor.A. Look B. Looking C. Looked D. Looking 看起来又累又虚弱，这个妇女应该休一天假去看医生。 （look在本题中不是实意动词，而是感观系动词，系

58、动词在非谓语中用主动式表被动。）例16._ smoothly, this kind of pen sells well in our school.A. To write B. Writing C. being written D. Written 因为写起来很流畅，这种钢笔在我们学校很畅销。 解析：动词如果不是表示动作，而是表示物体具有某种性质或特征时，往往用主动形式表示被动。原则八：演变成了介词或连词的分词。英语中有些词表面上看是分词，但实际上已经变成了介词，因此应该用ing形式还是分词ed形式已经变得约定俗成了。这时往往不适用非谓动词规则，而是看英美人士的习惯。例17_her age，s

59、he looks quite youngAConsider B. Considered C. To consider D. Considering解析：题意是：“就她的年龄而论，她显得十分年轻。”这里的considering表示“考虑到；鉴于”，它已经变成了介词，不管是“考虑还是被考虑”这里都用considering。高中阶段我们还学过的有：介词concerning关于regarding关于，given鉴于supposing假如原则九：当主从句主语一致，且从句中包涵系动词be时，主语和be 应同时省略。即连词+doing/done 例18 If _ another hour, I would

60、have finished it better.(give的恰当形式填空)。例 19. While _ homework, the boy likes listening to light music.(do的恰当形式填空)解析：18. given 是由if I was given another hour省略来的，if 在省略前省略后都是连词；19.doing 是由while the boy are doing homework省略来的，while在省略前后都是连词注意：before和after可以做介词，后面接动名词例201） After _ , he found a job as a secretary in a company.(graduate的恰当形式填空)2）Before_ a proper person to be the new president, the old president wouldnt resign.(select的恰当形式填空)解析： graduating/graduation after 这时是个介词，所以后面总是用动名词，如果改为after he graduated，那么这个after就变成了连词。2题中的before用法与after 一样，后面加句子时，是连词，后面只加一个动词时，要用动名词形式，并充当介词。所以2题填selecting