现在完成时疑问句只用have?今天看新概念第三册的第一课.课文前的问题是:Where must the puma have come from?为什么用have 疑问句一定用have?

问题描述:

现在完成时疑问句只用have?
今天看新概念第三册的第一课.课文前的问题是:Where must the puma have come from?
为什么用have
疑问句一定用have?

must have done 是固定词组,表示“一定做过某事”.
You must have passed the exam .你一定通过了考试