--- He has to finish the experiment today. He must be in the lab,____?---That s quite possibleA.mustn't heB.won't heC.doesn't heD.isn't he
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D解析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。