就是例如 you are a boy ,aren't you?陈述句部分是BE动词,疑问句部分也要用BE动词
you can jump ,cna't you?陈述句部分是情态动词,疑问句部分也一定要用情态动词.
you like jumping,don't you?陈述句部分是实意动词,那么 疑问句部分要用助动词代替实义动词
you have done your homework,haven't you?陈述句动词是有助动词+实义动词构成,那么疑问句用一个助动词代替.
简而言之：前BE则后BE,前助则后助,其他用助动.