情态动词+have+动词过去分词 * 表达过去事实 * 表达推测的含义（但助动词should除外） ``` He can/could have arrived.他可能已经到了。（可能性次之） He may/might have arrived.他可能已经到了。（可能性最小） He must have arrived. 他准是已经到了。（可能性最大） ``` * should+have+p.p 本应该··· ``` He should have arrived.他本来应该已经到了。 They should have finished the work.他们本来应该已经完成这个工作了。 ``` * needn't+have+p.p 本不需要··· ``` You needn't have done so.你本不需要那么做的。 ``` * must+have+p.p 准是已经··· ``` He must have arrived. ``` * can't+have+p.p 不可能已经··· ``` He can't have arrived. ```