这句英语为何用这个选项?

题目

这句英语为何用这个选项?
In the United States,bus travel doesn’t cost much as _______train travel,
A.don’t they B.does it C.do they D.doesn’t it
为何用了倒装句?

答案

这句话错了吧.
应该是：
In the United States,bus travel doesn’t cost much as train travel,_______?
A.don’t they B.does it C.do they D.doesn’t it
选B
考的是反意疑问句.你回头好好看看原体.