上述部分主句谓语是think,believe,expect,suppose,imagine等引导的定语从句,疑问部分与宾语从句相对应构成反意疑问句.
I don't think he is bright,is he?
We believe she can do it better,can't she?
所以
I think he must be right,isn't he?
(must be 在这里做情态动词,所以用is)