which side are you on?

问题描述:

which side are you on?
which side are you on
which side do you on?
哪个对,为什么?

which side are you on 是对的.
你在哪一边?
which side do you on?是错的,因为这个句子如果是个陈述句,没有实义动词,所以不能用do.