一般现在时：I listen 现在进行时：I am listening 过去进行时：I was listening
现在完成时：I have listened 现在完成进行时：I have been listening 一般将来时：I shall listen”或“I will listen.”
将来进行时：I shall be listening 一般过去时：I listened 过去完成时：I had listened
过去完成进行时：I had been listening 将来完成时： I shall have listened 将来完成进行时： I shall have been listening
He has worked for us for ten years.
Has he worked for us for ten years.
（1） by + 过去的时间点。如：
I had finished reading the novel by nine o"clock last night.
（2） by the end of + 过去的时间点。如：
We had learnt over two thousand English words by the end of last term.
（3） before + 过去的时间点。如：
They had planted six hundred trees before last Wednesday.
before或by the time引导的现在时的从句
He will have worked for us.=He will work for us.
should / would have done sth.
He said that he would have worked for us.=He said that he would work for us.
have/has been +-ing 分词
He has been working for us for ten years.=He has worked for us for ten years.
had been +-ing 分词
He said that he had been working for us for ten years.=He said that he had worked for us for ten years.
主语+ shall/will have been doing
He will have been working for us.=He will work for us.
would have been+现在分词用于其他人称
He said that he would have been working for us.=He said that he would work for us.