1) 一般式: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
疑问词
疑问词who,what,which,when,where,whether,how后可接不定式构成不定式短语,在句中作主语、宾语、表语等。如:
①When to leave for London has not been decided yet. (不定式在句子中做主语)
②Mr. Smith didn't know whether to leave or stay there. (不定式在句子中做宾语)
③I asked Professor Xu how to learn English well. (不定式在句子中做直接宾语)
④The question was where to get the medicine needed. (不定式在句子中表语)
以上例句中疑问词+不定式部分,均可转换为相应的从句形式。