(急!):It isn't easy for him to work out this problem.I thought.(合并为一句)

问题描述:

(急!):It isn't easy for him to work out this problem.I thought.(合并为一句)
It isn't easy for him to work out this problem.I thought.(合并为一句)I ___ ___ it ___ easy for him to work out this problem.

I thought that it wasn't easy for him to work out this problem.