They must have been to the USA,have not they?与He must have been...答:你好,你没有搞懂这些句子的用法:在这两个句子中,因为都没有时间状语的修饰,所以句子发生的时间不确定,答案也不确定,请你看以下的句子,They must have been to the USA,haven't they?He must have been to the USA,hasn't he?这两个句子都是对的,因为都没有时间状语,可以翻译为:他(们)到过...