He is not much of a cook.

他不是个好厨师。

　　not much of: not very good as 不很好
　　再如:
　　I'm not much of a mechanic, I'm afraid, but I'll have a look at your car if you like.
　　我恐怕不是一个很熟练的技师，但如果你愿意的话，我就看看你的汽车。