The dog I saw yesterday must be yours.
He can't be late this morning.
He must have been ill at that time.
She can't have been home last night.
英语翻译（对过去）肯定推测：must+ have＋动词的过去分词否定推测：can't＋have＋动词的过去分词我昨天见到
The dog I saw yesterday must be yours.
He can't be late this morning.
He must have been ill at that time.
She can't have been home last night.