情态动词表推测时，该句的反义疑问句和情态动词无关，必须去掉该情态动词后，考虑句子
谓语动词的发生时间和谓语构成，再进行相应的变化。
如：
1.
It
must
have
rained
last
night,
didn't
it?
去掉must后，考虑时间状语last
night，说明句子本该使用
一般过去时，即变成：It
rained
last
night，所以其反义疑问句为didn't
it?
再如：
2.
You
can't
have
been
to
Beijing
before,
have
you?
去掉can't后，根据句意，句子本该使用
现在完成时，即变成：You
haven't
been
to
Beijing
before，所以其反义疑问句为have
you?