学习 英文：值得留意的现在完成时

　　现在实现时
 

　　一、现在完成时的概念
现在完成时用来表示之前已发生或实现的动作或状态，其结果确切跟现在有联系。动作或状况发生在从前但它的影响当初还存在；也可表现持续到现在的动作或状态。学习 英文提供的结构为： have (has) +从前分词。

　　二、值得留意的个别用法：
动词个别是连续性的，如live, teach, learn, work, study, know.

举例：
I saw this film yesterday.
（学习　英文强调看的动作产生过了。）
I have seen this film.
（强调对当初的影响，电影的内容已经知道了。）　
Why did you get up so early?
（强调起床的动作已发生过了。）
Who hasn't handed in his paper?　
（学习　英文强调有卷子，可能为不公平竞争。）
She has returned from Paris.　
她已从巴黎回来了。
She returned yesterday.
她是昨天回来了。
He has been in the League for three years.
(学习　英文：在团内的状态可连续)
He has been a League member for three years.
(学习　英文：是团员的状态可连续)
He joined the League three years ago.　
( 三年前入团，joined为短暂举动。)
I have finished my homework now.　

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