it 用作形式宾语可以代替哪些成分
当不定式、动名词、从句等用作宾语且其后跟有宾语补足语时，就应在宾语补足语前使用形式宾语，而将真正的宾语移至句末。如：
1. 代替不定式
He found it easy to earn extra money. 他发现赚点外快很容易。
Foreigners find it difficult to learn Chinese. 外国人觉得中文很难学。
She found it difficult to answer the question. 她发现回答这个问题很困难。
Some teachers find it difficult to keep their classes in order. 有的教师发现课堂秩序很难维持。
Do you think it convenient to bring your lunch to school? 你觉得把午饭带到学校去方便吗？
The coughs of the people made it impossible to hear the speaker. 人们的咳嗽声使演讲人的话不能听到。
Having been his own boss for such a long time, he found it hard to accept orders from another. 自己当老板已经这么久了，他觉得难以听从别人的差遣。
2. 代替动名词
I found it interesting being back at school again. 我发现再次回到学校很有意思。
I find it interesting talking go you. 我觉得同你谈话很有意思。
I found it interesting being back at school again. 我发现再次回到学校很有意思。
You must find it exciting working here. 你一定会发现在此工作是很令人兴奋的。
He found it very hard teaching a class full of indifferent teenagers. 他发觉教一班无动于衷的十几岁的孩子真是头疼。
As a single father, he found it a struggle bringing up three children. 作为一名单身父亲，他发现带大三个孩子真不容易。
3. 代替从句
I thought it certain that he would be late. 我肯定他会迟到。
Jan thinks it funny that I’ve taken up yoga. 简认为我练瑜伽功是可笑的。
I find it amazing that you can’t swim. 你不会游泳可使我大吃一惊。
I didn’t think it likely that she would come back. 我认为她不可能回来。