Question

They must have finished the work by the end of last month, ______?

A. mustn't they B. haven't they C. hadn't they D. didn't they

Answer 1

选C，当情态动词must表推测时，其反义疑问句要根据实际情况来判断，本题的时间状语是by
the
end
of
last
month,应与过去完成时连用，还原一下本题应为：They
had
finished
the
work
by
the
end
of
last
month.所以要选C。

Answer 2

a
试题分析：句意：他们上个月的月底一定已经完成了这项工作，不是吗？当情态动词must表推测时，其反义疑问句要根据实际情况来判断，本题的时间状语是by
the
end
of
last
month,应与过去完成时连用，还原一下本题应为：they
had
finished
the
work
by
the
end
of
last
month.故选c。

Answer 3

B
在表示猜测的
反义疑问句
提问中，如果出现明显的时间表示，那么反义疑问句，
就根据这个
时间状语
来写，因为是by
last
month，所以用
过去完成时