he ____have completed his work ;otherwise,he would not be enjoying himself by the seaside.

填should还是must??? 解释，thanks

热心网友

must，表示肯定的推测。“他一定已经完成了他的工作，否则他不会在海滩游玩”。即使翻译成“应该完成”，也用must。should一般用于一般现在时中的“应该”，或者是虚拟语气中的“本来应该”。如：You should study hard. （一般现在时）We should have attended the party if we were not busy. （虚拟语气）

热心网友

he ____have completed his work ;otherwise,he would not be enjoying himself by the seaside.析：本句的大致意思我们可以理解为：他完成了作业才能去海边玩。should have done 本应该做某事（但没有做），句意思不通．must have done 表示一定做过某事，只有完成了作业，他才能去玩，否则就不，符合逻辑．