题目内容：

Tony finds _____ very difficult to learn Chinese well.
RT 答案是it,为什么不用it's?
是it's不是is

优质解答

find it difficult to do sth.是一个常用句式.
it为什么不用it's?
一、因为句中已经出现了一个谓语动词finds,如果用了it's,句中就出现了两个谓语动词,而这是不允许的（除非两个谓语动词是并列关系）.
二、it是形式宾语.to learn Chinese well是真正的宾语.这句话其实就是：
Tony finds to learn Chinese well very difficult.
Tony是主语；finds是谓语；to learn Chinese well 是宾语；very difficult是宾语补足语.
宾语太长,为了句子的平衡,就将宾语移到句尾,而在原宾语的位置上填上形式宾语it.