第1个回答 2006-03-05
当要用动词相关的动作作主语时,动词要用+ing形式.
Smoking is bad for your health.
用动词原形的几情况
1.加助动词do, does或did 的肯定句变成否定句时，其后面的动词要用动词原形；
He didn’t work hard at English last term.
2.情态动词后面要用动词原形；
Must I be at home tonight?
3.be going to, will, shall 等构成的将来时态，其后面的动词要用动词原形；
There will be on a new interesting film at the cinema.
4.祈使句要用动词原形；Be careful, Lin tao!
5.let开头的祈使句，其后面的动词要用动词原形；
Let’s have a look at the pictures.
6.had better 后面要用动词原形；
you’d better put on more clothes. It’s very cold outside.
7.why not 之后要用动词原形；
Why not come a little earlier?= Why don’t you come a little earlier?
8.动词不定式to之后要用动词原形；
Please give me something nice to eat.
9.feel, hear, see, watch 等感官动词之后要用动词原形。如果表示这一动作正在进行，就用现在分词。
Sometimes we can hear a girl sing in the room.
I feel my left leg hurting badly.
那些都是我自己总结的,仅你参考.本回答被提问者采纳
第2个回答 2006-03-05
首先说，动词原型开头的句子只可能是祈使句。
比如，Wish you every success.
壮语从句前置的时候是以动词的分词形式开头，这样的例子有很多
Lying in bed, he fell asleep.
顺便多说几句：
给你解释现在分词、过去分词开头的句子的用法：
1. 当从句的主语和主句主语一致时，用现在分词
2. 当从句的主语和主句主语一致但是被动形式时，用being done
3. 当从句动作发生时间和在主句之前时，用过去分词的形式
4. 当从句动作发生时间和在主句之前且是持续动作时，用having been doing
5. 当从句动作发生时间和在主句之前且主语被动，用having been done
……
举例：
1. (he)Lying in bed, he fell asleep.
如果将此句还原，是He fell asleep when he lied in bed.主句从句主语都是he
2. Being told the bad news, he bursted into tears.
3. Finished his work, he went out.
……