现在完成时

1形式：have 过去分词; has 过去分词

Eg. I have finished my homework. 我已经写完了我的家庭作业

He has returned from school. 他已经从学校回来

2.用法

1.表示截止到现在已经完成的动作

eg By now, I have collected all the data that I need.

2.表示发生在过去而对现在产生影响、带来结果的动作

eg She has been to the United States.

3.表示过去发生的动作持续到现在，并可能还要延续

eg I have learned English for 8 years.

　　过去完成时：

had 过去分词

1.发生在“过去的过去”

eg When I woke up, it had stopped raining.

2.与一个表示过去的时间状语连用

eg Peter had collected more than 300 Chinese stamps by the time he was ten.

3.在过去某时之前开始一直延续到这一时间

eg By the end of last year, he had worked in the factory for twenty years.

过去将来时

1.宾语从句或间接引语中

eg He didn’t expect that we would all be there.

2.表示过去习惯性的动作

eg During that period, he would do this every day.

3.表示过去的愿望、倾向，多用于否定句

eg They knew that we would never permit such a thing.

一般过去式

标志性词：yesterday, the day before yesterday, two years ago, last month

the other day 不久前一 天 in 19999 (在过去的年月)

　　现在进行时

标志性词：now, look! Listen!

Look, they are playing basketball.

Listen, she is singing.