‘你明知道法语没用还要学，你有毛病啊！’怎么翻译？

You clearly know French is useless and you still want to learn. What is wrong with you!

You clearly know..., you still ....

You know France is unuseful but still keep learing,are you simple-minded?

你明知道法语没用还要学，你有毛病啊

You knew it is unuseful to learn French,how come you still get into it?What's wrong with you?

you already know ...but

It is clear that