一、完成时态 have + done（过去分词）

4中失态

I have done my homework by now. //现在完成时

I had done my homework by last week. //过去完成时

I will have done my homework by next work. //将来完成时

Yesterday I said I would have done my homework by next week. //过去将来完成时

现在完成时态

1、过去发生的动作对现在影响或结果。常用already、just

I have already bought a car. //alread 

2、过去发生的动作一直持续到现在。  常用for、since

I have studied English for ten years.

二、

haha