Mary must have gone to the cinema when I went to see her yesterday,__?

来源：百度知道 编辑：UC知道 时间：2024/06/17 20:20:13
A.didn't she
B.mustn't she

why we choose A

must have gone 这里的 must + 完成时态 ，表示 猜测
还原：
Mary went to the cinema when I went to see her yesterday, didn't she?

肯定： must have done
否定： cant have done
可能： may have done
以上是对过去时的猜测

现在时的猜的
肯定 must be
否定 cant be
可能 may be

must 做情态动词时只用在肯定句，不能用在否定和疑问句中。
所以，这里的反义疑问句只能借助于助动词did。

must have done表示对过去的猜测