问题
选择题
--- He has to finish the experiment today. He must be in the lab,____?
---That s quite possible.
A．mustn't he
B．won't he
C．doesn't he
D．isn't he
答案
D
该题考查反意疑问句中尾句部分的助动词用法，must be结构中的中心词应为be，且He must be in the lab相当于I think he is in the lab，故其尾句部分为isn't he。