：
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。
动名词与不定式
1) 动名词与不定式的区别：
动名词表达的是： 状态，性质，心境，抽象，经常性，已发生的
不定式表达的是： 目的，结果，原因，具体，一次性，将发生的
2) 接不定式或动名词，意义相同。
3) 动名词与不定式语义不同的有11 组：
stop to do stop doing
forget to do forget doing
remember to do remember doing
cease to do cease doing
try to do try doing
go on to do go on doing
afraid to do afraid doing
interested to do interested doing
mean to do mean doing
regret to do regret doing
begin/start to do begin/start doing
特殊词精讲
stop doing/to do
stop to do停止，中断做某事后去做另一件事。
stop doing停止做某事。
They stop to smoke a cigarette.他们停下来，抽了根烟。
I must stop smoking. 我必须戒烟了。
