时态\语态　　　 主动　　　　　被动
一般式　　　　　 to do　　　　　　to be done
进行式　　　　　 to be doing　　
完成式　　　　　 to have done　　 to have been done
完成进行式　　　 to have been doing　　

1) 现在时：一般现在时表示的动词，有时与谓语动词表示的动作同时发生，有时发生在谓语动词的动作之后。
　　He seems to know this.
　　I hope to see you again. = I hope that I'll see you again.　我希望再见到你。

2) 完成时：表示的动作发生在谓语动词表示的动作之前。
　I'm sorry to have given you so much trouble.
　He seems to have caught a cold.

3) 进行时： 表示动作正在进行，与谓语动词表示的动作同时发生。
　He seems to be eating something.

4) 完成进行时：
　She is known to have been wreaking on the problem for many years.