1. must have done表示对过去发生的事情的肯定推测, 意为“一定做了……”, 该结构只用于肯定句中。
*(2019·天津高考)I must have always known reading was very important because the first memories I have as a child deal with books.
我一定一直都知道读书很重要, 因为我小时候的第一印象就是读书。
*It must have been a rough copy — there were so many corrections.
那一定是一份草稿, 修改的地方太多了。
*He reasoned that since she had not answered his letter she must have left here.
他推断, 由于她没有给他回信, 她一定是已经离开这里了。
