1、9上Unit 4 Growing up,Grammar （1）,after,at an earlier time than,at a later time than,A Using before, after, when and while,一.before and after,How to use beforeBefore means earlier than a certain time a. 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
2、man almost knocked me 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 m
3、onths went by before Tom 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.” It was a long time before we met again.过了很久我们才再次见面 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
4、graduate from this school . It will be not long before you find you are wrong .,2.How to use after,After means later than a certain time a.after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(有时也用现在完成时)，而不能直接用一般将来时。如： 误：Ill tell him after you wil leave. 正：Ill tell him after you leave (或have left). 你走了之后我再告诉他。 b.选择一般
5、现时或现在完成时(表示将来意义)的基本原则是：如果强调从句 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 生，或几乎同时发生(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)，多用一般现在时(有时 两种时态都可以)。如； Ill leave after he comes back. 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
6、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
7、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 years after. 20年后他回来了。,二.when and while,1. How to use when and whilea. 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whe
8、n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。 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 te
9、acher 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 children were running to move the bag of ricewhen 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
10、。,三.Exercise one. I: Help David combine his sentences using before, after, when or while. 1. I go jogging every morning. Then I have 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 un
11、cle.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 practised 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 t
12、o 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. _ 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.,remained,before,took notice of,After,graduated,was forced,When,got the chance,scored,While attending,tried out for,Homework,1. Prepare for Grammar B and C. 2. Do after school exercises.,Goodbye,
