"发现某事很难"是"find it difficult to do" 还是"find it is difficult to do"?

问题描述:

"发现某事很难"是"find it difficult to do" 还是"find it is difficult to do"?
我做题的时候真题解释是"find it difficult to do",但difficult不是形容词吗,怎么前面不用加be动词的?

答案不错
find it difficult to do = find that it is difficult to do
find something +形容词+to do固定句型