Bob said he was going to join our club but he didn’t. What a shame! He ______ his mind.A.can’t have changedB.mustn’t have changedC.wouldn’t have changedD.shouldn’t have changed
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D解析考查情态动词与虚拟语气。shouldn’t have done 本不应该做某事而实际上做了，can’t have done/ wouldn’t have changed表示对过去的推测，不可能，must表推测不用于否定句中，句意：鲍勃说要加入我们的俱乐部但是他没来。多遗憾呀，他本不应该改变主意的。故选D。