完成时什么时候用

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完成时什么时候用

完成时什么时候用
完成时什么时候用

完成时什么时候用
现在完成时用法
⑴ 与just连用,表示刚刚完成的动作或状态(just放在have∕has与P.P.之间).
I have just had lunch.
He has just finished his homework.
⑵ 表示动作发生在过去,持续到现在,有可能延续到将来,常与since“自从…”
(一点时间)for(一段时间)连用.
I have learned English since 2000.
He has lived there for 10 years.
⑶ 表示过去的动作对现在的影响.
He has lost his key.
⑷ 与最高级连用,表示“到目前为止最…”
You’re the cleverest girl that I’ve seen.
⑸ 与It∕This the first time that…连用,表示“第一次……”
It∕This is the first time that he has learned English.
⑹ have∕has been to…
曾经去过…(已归)
have∕has gone to…
去了…(未归)
I have been to Shanghai.
Tom has gone to Shanghai.

一个动作或过程到某个时间点之前就已经全部结束了。
I've done my homework. 现在完成时-在说话前就已经做完作业了。
I'd finished homework by the time my father got home. 过去完成时-我爸到家前我就做完作业了,在过去某点之前已经完成的动作。