将来完成时:

1.构成:shall / will have + 过去分词

2.功能:表示将来某时之前已经完成的动作。

→They will have been here for 5 years next Friday.

→By the end of next term, the students will have finished the book.

 

过去将来完成时

1.构成:would / should have + 过去分词

2.功能:表示从过去某个时间看将来某时之前已经完成的动作。

→He said that they would have arrived by seven o'clock.

 

将来完成进行时:

1.构成:shall / will have been + 现在分词

2.功能:表示某一动作将继续到将来某时,且该动作此时尚未发生。

→We shall have been staying here for four weeks when Tom arrives.

→It will have been raining for a week if it does not stop tomorrow.

注:此句型过于复杂,人们很少运用,了解而已。