The problem is so difficult that I can't work it out.同义句

问题描述:

The problem is so difficult that I can't work it out.同义句
The problem is _______ _______ difficult for me ______ work out.

that too ...to对吗?对的吧,有正确答案出来时,希望能加个评论。我们老师讲了,是 far tooto