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1、Unit 4 Growing upUnit 4 Growing upGrammarafterbeforeat an earlier time thanat a later time than 一一.before and after1.How to use before Before means earlier than a certain timea. 表示“在.之前就.”。 Mary had finished her homework before her mother returned. b. 表示“过了多久后才 ，动作进行到什么程度才” The man almost knocked me
2、 down before he saw me . They walked about 30 miles to the west before they saw a village . They worked day and night about three days before everything returned to normal . c. 表示“刚就”I had hardly sat down before the bell rang. d. 表示“不知不觉就.； 还没弄清就”Time passed quickly and three months went by before T
3、om knew it. e. 用于句型“it was +时间段+ before ” 表示 “过了多久才” It was three days before he came back. . f. 用于句型“ it was not long +时间段+ before ” 意为“不久就.” g. 用于句型“it will be(not )+时间段+ before.”表示“要过多久/ 不久才” It will be half a year before you graduate from this school . It will be not long before you find you are
4、 wrong .2.How to use after AfterAfter means later than a certain time means later than a certain timea.a.afterafter引导的时间状语从句如果具有将来意义，往往引导的时间状语从句如果具有将来意义，往往要用一般现在时来表示要用一般现在时来表示(有时也用现在完成时有时也用现在完成时)，而不能，而不能直接用一般将来时。如：直接用一般将来时。如： 误：误：Ill tell him after you wil leave. 正：正：Ill tell him after you leave (或或
5、have left). 你走了之你走了之后我再告诉他。后我再告诉他。 b.b.选择一般现时或现在完成时选择一般现时或现在完成时(表示将来意义表示将来意义)的基本原的基本原则是：如果强调从句则是：如果强调从句 动作在主句动作之前完成，则用动作在主句动作之前完成，则用现在完成时；如果强调主从句动作同时发现在完成时；如果强调主从句动作同时发 生，或几生，或几乎同时发生乎同时发生(尤其是当从句的谓语动词是尤其是当从句的谓语动词是get, arrive, see, hear, leave, return等表示迅速完成的动作的动词时等表示迅速完成的动作的动词时)，多，多用一般现在时用一般现在时(有时有时
6、两种时态都可以两种时态都可以)。如；。如； I Ill leave after he comes back. 他回来后我就离开。他回来后我就离开。 c. 一般说来，如果在过去某一时间内先后发生了两个动作,那么先发生的动作用过去完成时，后发生的动作用一般过去时。但是若用连词after 来连接这两个动作，由于after本身已说明了两个动作的先后关系，所以两者均可用一般过去时。如： After he (had) closed the door, he left the house. 关了门之后，他就离开了家。 d. 有时以连词after引导的时间状语从句可以换成一个以介词after引导介词短语或以连
7、词after引导的分词短语，而意义不变。如： He went to school after he had breakfast (=after breakfast). 吃了早饭之后，他就去上学了。 After l had finished (=After having finished / After finishing / Having我干完活后就去睡觉了。 e. after还可用作副词，意为“后来”或“(一段时间)以后”，通常要放在另一时间副词之后。如： We arrived soon (或just / shortly) after. 我们不久就到了。 He returned twenty
8、 years after. 20年后他回来了。 二.when and while1. How to use when and while a. when means at or during a certain time 既指时间点，也可指一段时间； while means during a certain time只指一段时间，因此when引导的时间状语从句中的动词可以是终止性动词，也可以是延续性动词，而while从句中的动词必须是延续性动词。 b.when 说明从句的动作和主句的动作可以是同时，也可以是先后发生； while 则强调主句的动作在从句动作的发生的过程中或主从句两个动作同时发生
9、。 c.由when引导的时间状语从句,主句用过去进行时，从句应用一般过去时;如果从句和主句的动作同时发生,两句都用过去进行时的时候,多用while引导 如： 1). When the teacher came in, we were talking. 当此句改变主从句的位置时，则为： While we were talking, the teacher came in. 2). They were singing while we were dancing. d. when和while 还可作并列连词。when表示“在那时”；while表示“而，却”，表对照关系。如： 1). The chil
10、dren were running to move the bag of rice when they heard the sound of a motor bike. 孩子们正要跑过去搬开那袋米，这时他们听到了摩托车的声音。 2). He is strong while his brother is weak. 他长得很结实，而他弟弟却很瘦弱。 三.Exercise one.I: Help David combine his sentences using before, after, when or while.1. I go jogging every morning. Then I h
11、ave breakfast.2.I practised playing basketball for hours. I felt tired out.3. I met Peter. I was waiting at the bus stop.4. I was watching TV. I received a call from my uncle.5.I was ready to go to bed. My father came back from work.I go jogging every morning before I have breakfast.After I practise
12、d playing basketball for hours， I felt tired.I met Peter while (I was) waiting at the bus stop.While (I was) watching TV,I received a call from my uncle.I was ready to go to bed when my father came back from work.II:Put these sentences into English.1. He_ there for about a year_ the NBA_ _ _ him.2._
13、 he_ , he _ _ to play in another basketball league.3._ he finally _ _ _, he_ 20 points in his first game.4._ _ junior high, Spud _ _ _ the school team.remainedbeforetook notice ofAftergraduatedwas forcedWhengot the chance scoredWhile attendingtried out forHomeworkHomework 1. Prepare for Grammar B and C. 2. Do after school exercises.