It作形式主语及形式宾语题(这也是一个常考点，it本身是没有意思的，注意it还可以指时间，天气等。)
　　1、It is difficult to study English well.
　　2、We think it is important to pass the exam

　
强调句型(要记住的是it is (was)……。that…。，如果前面是it iswas 后面往往选用that，当然强调人的时候也可用who)
　　1、It was at an evening party that I first saw her.
　　2、It is what you will do that is important.
　　3、When was it that he bought a new car