Question

They had to walk here because all the buses had l

They had to walk here because all the buses had left, ___they？
A. must‘t B. didn't C. hadn't
选哪个？为什么？

Answer 1

B
如果陈述句的谓语动词含有have to, had to时,反意疑问句通常用其适当形式。例如:
We have to get there tomorrow, don't we?
They had to take the early bus, didn't they?

追问

第二种为什么用过去式呢

根据had left？

追答

had to 过去时呢 所以，过去时。

Answer 2

B

追问

为什么

追答

记住：have to / has to / had to do sth. 句型变化时，用助动词 do / does /did ...

牢记在心，熟练运用，确保正确哦！