①提出将来会发生的事:
主句:主语+would/should/might/could+动词原形
eg. If he should go to Harvard University, he would make full use of his time.
如果他要上哈佛大学的话,他就会充分利用他的时间了。
主句:主语+would/should/might/could+动词原形
从句:动词过去式
eg. If he studied at this school, he would know the enviornment around the school very much.