There used to be lots of old city walls in beijing 的反意疑问句
问题描述：
There used to be lots of old city walls in beijing 的反意疑问句
答
There used to be lots of old city walls in beijing,usedn't there?
如果陈述句部分的谓语含有used to,其反问部分既可用use(d)n’t,也可用didn’t.例如：
There used to be some trees in this field,use(d)n’t / didn’t there?
You used to smoke a pipe,use(d)n’t / didn’t you?