现在完成时和过去完成时（Present Perfect Tense & Past Perfect Tense） 

一、现在完成时 (Present Perfect Tense)

1. 构成：have / has + 动词过去分词

2. 功能： (1) 表示过去发生的动作或事情，但与现在有联系或对现在有影响。常和一些表示不定时间的状语连用，如already, ever, yet, just, never, recently等。如：

a. She has just left.

b. Have you ever been to Shanghai?

c. I have been very busy recently.

(2) 动作发生在过去，并持续到现在，并且可能将继续持续下去。常和一些表示一段时间的状语连用，如since和 for 引导的短语。如：

a. He has worked in this city for ten years.

b. I have lived here since 1980.

c. We have studied English for five years.

(3) 现在完成时与一般过去时的区别：两者都表示发生在过去的动作或事情，但现在完成时强调动作与现在有联系、对现在有影响或仍将持续下去，而一般过去时表示动作已经结束，与现在没有联系。此外，现在完成时不能同明确表示过去时间的状语连用。 

如：a. We have lived in Shanghai for five years. 

     我们在上海生活了五年。(现在还在上海。)

b. We lived in Shanghai for five years. 

     我们曾在上海生活了五年。(现在不在上海了。)

c. My father has taught English all his life.

    我父亲教了一辈子英语。(现在还在教。)

d. My father taught English all his life. 

    我父亲教了一辈子英语。(现在不教了。)

e. The old man has died. 老人已经死了。

f. The old man died last night. 老人昨晚死了。

g. I have read the book. 我已经读了这本书。

h. I read the book last week. 我上周读了这本书。

二、过去完成时 (Past Perfect Tense)

1. 构成：had + 动词过去分词

2. 功能：

(1) 表示过去某个动作或某个具体时间之前已经发生、完成的动作或情况，多用在从句中。如：

a. I knew I had met her before. 

    我知道我以前遇见过她。

b. By one o’clock we had finished our homework. 

    一点钟的时候我们就已经做完作业了。

c. They had got the news before I came. 

    我来之前他们就已经知道那个消息了。

d. She had hardly gone to bed when the bell rang. 

    她刚刚睡下铃就响了。

e. The film had already begun when we got to the cinema. 

    我们到达电影院时电影已经开演了。

(2) intend, expect, hope, mean, want, suppose, plan等动词的过去完成时可以表示过去未曾实现的愿望、打算等。如：

a. I had expected to meet you, but you had left when I arrived. 

   我本想跟你见上一面的，但我到达的时候你已经离开了。

b. He had hoped to offer help, but he was out of town that day. 

    他本想帮忙，但那天他出城了。

c. I had intended to visit you, but my illness prevented me from doing so. 

    我本想去拜访你，但我因病没能成行。