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(共13张PPT)
现在完成时
现在完成时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。
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.(√)
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. My brother joined the army two years ago. 我弟弟参军两年了。
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.
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.
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。
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.
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 parts of 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
7.I'm not feeling well. I've caught a cold for three days. A B C D
8.Tom has caught a bad cold for days and he has
A B
stayed in bed since last Saturday. C D

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