G:现在完成时棗表示到目前为止已经完成，并对现在留下某种后果和影响的动作。
结构：助动词have/has + 动词的过去分词
用法:
1.表示过去发生的某一动作对现在造成的影响或结果,常与一些时间状语,如:already, yet, ever, never, just, before, once,twice等连用,也可以和包括现在在内的时间状语,如these days,today,this year,so far等连用.eg.I have already posted the letter. (信已经不在我这儿了)
2.表示过去发生的动作或存在的状态,一直持续到现在,也许还将继续下去,可以和表示从过去某一时刻延续到现在的一段时间的状语连用,即for +时间段,since+时间点/从句, in the last ten years等,谓语只可用延续性动词.
解析： 1.英语动词根据词义可分为两种,一种是延续性的,一种是终止性的,终止性动词(也可称为非延续性动词,瞬间动词,或点动词),如begin,start,die,buy,leave, come等,表示动作的发生与结束于一瞬间完成,不能再延续,所以它的现在完成时不能和表示延续的时间状语连用,即不能与表示一段时间的状语,for+时间段, since+时间点/从句连用,也不能用在how long引导的特殊疑问句中.
eg. I’ve left Shanghai for three days.(×) I’ve been away from Shanghai for three days.( √ ).
I left Shanghai three days ago. ( √ ) It is /has been three days since I left Shanghai.( √ )
2.初中英语课本中常见终止性动词有:leave, go, come, arrive, begin, buy, borrow, die, join, become等.终止性动词要表示持续时, 可用以下方法:
⑴.将时间状语改为时间段 + ago,句中谓语动词用一般过去时.
eg.我弟弟参军两年了. My brother joined the army two years ago.
⑵.若保留for+时间段,since+时间点/从句, 或用在 how long 句型中,则需将终止性动词改为相应的状态动词或延续性动词
常见终止性动词与延续性动词(或状态动词)的对应关系如下
come/go/arrive/get/reach/move------be in/at open-----be open
die------be dead close----be closed become---be borrow---keep begin/start-----be on put on----wear
leave-----be away (from) buy-----have fall asleep----be asleep
end/finish-----be over catch a cold-----have a cold
join the army----be in the army be a soldier join the Party----be in the Party be a Party member
→My brother has been in the army for two years. →My brother has been a soldier for two years.
3.现在完成时中been to,gone to和been in/at been to去过某地,表示某人的一种经历,可以和once,twice,already,ever,never等连用. eg. She has been to Shanghai twice. (表示目前人在这里)
gone to 去某地了,说话时某人已离开此地,在去某地的途中或已在某地,
eg. She has gone to Shanghai。 (表示现在她人不在这里)
been in/at 逗留在某地(已经一段时间).常和for ten days,since I came here等连用.
eg. She has been in Shanghai since she moved there.
4.现在完成时和一般过去时的区别
现在完成时所表明的是过去发生的动作对现在的影响,强调的是现在的情况,不可以和表示过去的时间状语yesterday,in 1991,three days ago last time,last night等连用一般过去时表明的是过去发生的事实,和现在不发生关系.
5.现在完成时中的 for 与 since
for + 时间段 与延续性动词的现在完成时连用 since + 时间点/从句
I have kept the library book for a week.= I have kept the library book since a week ago.
6. It is /has been +一段时间 + since 从句.自从某事发生已有一段时间了. eg. It is /has been two years since my brother joined the army. 注意:1.since 引导的从句中动词用过去时
2.when 引导 的特殊问句不与现在完成时连用.
3.have got,has got 虽然是现在完成时,但have got=have has got==has
练习题: 1.It’s a long time since we ____ (meet) last,isn’t it?
2.--I know you _______ (choose) a picture book among these. --Yes,Have a look at it, please.
3.So far,spaceships without people _______ (reach) the moon and some other partsof the universe.
4.My father____ home for nearly three weeks.
A.has gone away from B.has left C.has been away from D.went away
5.Mr and Mrs Green have_____in China for a week. A.been B.got C.arrived D.reached
6.--Where’s Mary? --Oh,she _____the library.
A.has gone to B.went to C.has been to D.had gone to
H:过去完成时棗表示过去某一时间或动作之前已完成的动作
结构： 助动词had + 动词的过去分词
用法： 1.表示在过去某一时间或动作之前已经发生或完成了的动作,动作发生的时间为“过去的过去“.表示过去某一时间可用by,before 等构成的短语,也可用when,before等引导的从句或通过上下文表示. eg. By the end of last term,we had learned a thousand English words.
He had finished his homework before his father came back last night.
2.表示过去某个时间之前发生的动作或状态, 一直延续到这一过去时刻,或还将继续下去. eg. When I got to know him, he had worked there for twenty years.(注意) 否定式 had not == hadn’t
时态的呼应
1.主句中谓语动词如果是现在时或将来时,从句中的谓语动词可以用任何所需要的时态, he wants to speak to the headmaster. He said that he won’t be free tomorrow. he came last night.
2.主句中的谓语动词如果是过去时态,从句中的谓语动词一般情况下要用过去时态的某种形式. He said that he was working hard on his Chinese.
he had a very good journey home. he hadn’t bought the present yet.
he would stop in Moscow on the way. 3.如果从句所述内容是客观真理,则谓语动词总是用一般现在时,而不受主句中谓语动词时态的影响.
eg. Miss Gao told us that light travels much faster than sound.
4.时间或条件状语从句中,若主句是一般将来时或祈使句,从句要用一般现在时代替将来时.
eg.Stop talking when the headteacher ______(walk)into the classroom.
Jim won’t watch TV until he ___ (finish) his homework every time.
练习题： 1.They were so pleased to see each other that they almost ____ (forget) everything else around. 2. The girl put on her dress and then _______ (go) to the mirror to look at herself.
思考题： 1.I____(leave)my ruler at home. Can I use yours?
2.Who’s Jack London? I ___ never ____ (hear) of that man before.
3.I’m afraid I ___ (keep) you waiting for such a long time.
4.--Where ___ you___ (be)? --I’m looking for you all the time.
5.____they____ (know) each other when they were young?
6.The baby will cry if she ___ (not see) her mother
