I find it difficult to learn English well.这里,为什么不是it is diff

I find it difficult to learn English well.这里,为什么不是it is diff 为什么是“I find it difficult to learn English well?" I find it difficult to learn English这句中为什么不是it is difficult I find it difficult to learn English well的复合句 I find it difficult to learn English well,Professor Smith I find it's difficult to learn English well.改同义句 I find it _ 将I find it is useful to learn English well. I find it difficult to learn English well【改简单句】 We find it important to learn English well.为什么是it不是it's I find it difficult to learn math well It is not difficult to learn English.___ ___ ___ is not diff I think it diffcult to learn English well.为什么it后面不is?it在这里的作