文档介绍：to do和 doing 作主语的区别
is permitted here (smoke).
It is not very good for you so much (smoke).
2. more is necessary (read).
It is quite necessary it again(read).
3. a language in one month is impossible. (learn)
一般来说,表示比较抽象的行为动作时多用doing;
表示比较具体的某次行为动作时多用不定式to do。
1. (climb) mountains is interesting.
1 (drive) a car during the rush hour must be tiring.
2. puters is my job.
sell
3. (teach) English is my job.
1 (teach) you English this term is my job.
doing作主语时,通常用以表示一件已知的事或经验。
to do通常用来表示一件未完成的事或目的。
doing 作主语时强调的是做那件事的持续状态,
to do 作主语时主要表示现在或者将来的事情
1. 学一门外语非常重要。
2. 覆水难收。
3. 放弃这一机会是个遗憾。
4. 撒谎没好处。
5. 与其诅咒黑暗,不如燃起蜡烛。
It is very important to learn a foreign language.
It is useless crying over the spilt milk.
It seemed a pity to give up the chance.
It is no good telling lies.
It would be better to light up candle than to curse the darkness.
It + be + 形容词/名词词组+ to do sth. / doing / that ….
不定式to do作主语时,常使用形式主语结构;而doing作主语时,较少用形式主语结构,

只有在 It is + no use, no good (fun, a great pleasure, a waste of time...)等名词+doing sth.

It is + useless (senseless, nice, worth等形容词)+ doing sth.
It is hard to make him change him mind.
It is no good objecting.
It is useless speaking.
It is not an easy thing to master a language.
It is a great fun playing football.
How would it be to start tomorrow?
It is a waste of time trying to explain.
It took all his strength to move out of the crowds.
It is nice seeing you again.
Business is business and it will not do to be so careless.
It is no good pretending to know what you don't know.
It is worth learning another language.
逻辑主语
for the young, the children
It is useless crying over the spilt milk.
It seemed a pity to give up the chance.
It is no good telling lies.
It’s very kind to help me with the work.
It seemed selfish not to share his dictionary with others.
It + be + 形容词+ (for sb.)+ 动词不定式
这类句型常用形容词easy, difficult, hard, important, possible,wise等作表语,为了强调不定式的逻辑主语,
常在不定式前加for sb,译为“对某人来说做某事怎