1、请问什么时候用ing做主语 什么时候用 to do
3个回答

1、动名词做主语往往表示普通的、一般的行为,不定式做主语常表示某次具体的行为.例如:

Collecting information about children’s health is his job.收集有关儿童健康的信息是他的工作.

It’s necessary to discuss the problem with an experienced teacher.与一位有经验的老师讨论这个问题是有必要的.

2、常用不定式做主语的句型有:

(1)It’s difficult (important,necessary) for sb.to do

(2)It’s kind (good,friendly,polite,careless,rude,cruel,clever,foolish,brave) of sb.to do.

3、常用动名词做主语的句型有:

It’s no good (use,fun) doing.

It’s (a) waste of time one’s doing.

ps:“collecting the information about childrens health”只是暂时行为,又不是一直都在收集.