I find it hard to believe that+从句分析?这段话怎么分析啊,I和it哪个是主语?that 引导的是补语从句还是?

当然I是主语，that引导的是believe的宾语从句

I 是主语，it 是所谓 “形式宾语” - that 作为连词引导的从句是 “事实宾语”。
例如：
I find it hard to believe that (I passed the test.)
= I find (my passing the test) hard to believe.

主句是I find it. it是形式宾语,真正的宾语是to do不定式,即to believe that+从句, hard是it的补足语.而在to do不定式中believe有跟了一个宾语从句,即that从句.其实这句话可以这样分开理解,意义上：
我觉得believe that+从句... 是hard的.