英语语法:动词时态(现在完成时)
#英语时态#
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1. 表示发生在过去的或已经完成的对现在仍有影响的动作。
I have lost my key.
I have already seen the film.
2. 表示一个动作或者状态发生在过去,并持续到现在,可能还要持续下去;
常和“for+时间段”或者“since+时间点/从句”连用,这时只能用延续性动词。
Mr. Zhang has taught English for 20 years.
3. 几个副词在现在完成时中的用法
(1)just
意为“刚刚”,表示动作刚刚结束,常放在助动词与过去分词之间。
He has just come back from America.
(2)ever
意为“曾经”,用于疑问句和否定句中,放在助动词和过去分词之间。
Have you ever been to London?
(3)never
意为“从来没有”,常与before连用,放在助动词和过去分词之间。
I have never been to Beijing before.
(4)before
意为“以前”,指过去不确定的某个时候,总放在句末。
I have never heard of this singer before.
4. 延续性动词和非延续性动词在现在完成时中的用法
现在完成时可表示动作从过去某个时候开始一直持续到现在,与一段时间连用时谓语动词必须是延续性动词,非延续动词不能和一段时间连用。
例如:
我离开家乡已有10年了。
误:I have left my hometown for 10 years.
正:I have been away from my hometown for 10 years.
非延续性动词若与一段时间连用,必须转换为延续性动词。
常见的情况如下:
buy→have;
borrow→keep;
open→be open;
close→be closed;
begin/start→be on;
come→be her
go→be there;
die→be dead;
catch a cold→have a cold;
fall asleep→be asleep;
join→be in/be a member of leave→be away
常与现在进行时连用的时间状语有:
already, yet, never, ever, just, so far, up to now, until now, by now, in the past/last few years, for+一段时间,since+时间点/从句。