1) 现在式：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。一般为：动词+ to do something
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) 完成式：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)进行式：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)完成进行式：
She is known to have been wreaking on the problem for many years.
一般在表示情绪的动词后加to do也表将来
。