情态动词 + have done
对过去发生的事做推测、表示后悔或批评。
should have done（本该做却没做）/ can't have done（不可能做过）
要点
- should have done：本应该做但实际上没做，含批评或后悔。
- shouldn't have done：本不该做却做了。
- could have done：本来有能力做却没做。
- must have done：对过去的肯定推测，「一定做过」。
- can't / couldn't have done：对过去的否定推测，「不可能做过」。
- needn't have done：本来不必做却做了。
例句
You should have told me earlier.
你本该早点告诉我。
He must have missed the bus.
他一定是没赶上公交。
She can't have finished it so soon.
她不可能这么快就做完了。
I needn't have bought so much food.
我本来不必买这么多吃的。
She might have taken the wrong bus.
她也许是坐错了公交车。
We could have won, but we gave up too early.
我们本可以赢，只是太早放弃了。
易错提示
- 这类结构一律指「过去」，别和 should do（现在/将来应该做）混在一起。
- 否定加在情态动词后面：shouldn't have done、can't have done。
- might have done 是这一族里语气最弱的：He might have forgotten.（他也许是真忘了）—— 比 could have done 更不确定。
- 阅读里常见的等价说法是 was / were supposed to：You were supposed to call me. = You should have called me.（意思一样、结构不同）