情态动词 + have + V3

情态动词 + have + 过去分词 用来推测或评价一件已经发生的事。have 永远不变——不管主语是什么，都不用 has 或 had。

💡口语中 have 几乎听不见：must've /ˈmʌstəv/、should've、could've、might've——听起来像 “must of”。书写时一定要写 have，而且 have 后面用过去分词（gone、seen），不用一般过去时（went、saw）。

根据你有多确定来选择情态动词：

• Nobody's answering. They must have gone out.

  没人接电话。他们一定是出去了。

• I may have left my wallet in the taxi.

  我可能把钱包落在出租车上了。

• Minh can't have written this — he doesn't speak French.

  这不可能是阿明写的——他不会说法语。

• She couldn't have known about the party. We kept it secret.

  她不可能知道聚会的事。我们一直保密。

must have（表示推测时）的否定通常是 can't have / couldn't have。美式英语也常用 must not have + V3 表示“我肯定这事没发生”（He must not have seen me），但缩写 mustn't have 很少用。注意 couldn't have（不可能）比 might not have（也许没有）语气强得多。

同一个情态动词：+ 动词原形 说现在，+ have V3 说过去。见“推断：must / can't”一课。

should have + V3 = 本该这样做（但实际没做）；shouldn't have + V3 = 本不该这样做（但实际做了）。用来表示后悔或批评。ought to have 意思相同，但不太常用。should have 还可以表示“按理说现在应该已经……了”。

• We should have booked a table — the place is full.

  我们本该订个位子的——店里已经满了。

• You shouldn't have said that to her.

  你不该对她说那种话。

• You ought to have asked before borrowing my bike.

  你借我自行车之前本该先问一声。

• The parcel should have arrived by now.

  包裹按理说现在应该已经到了。（按预期）

• could have + V3：本来有可能，但没有发生；也可以表示轻微的抱怨（You could have told me!）。
• couldn't have + 比较级：不可能更好 / 更糟了。
• would have + V3：你本来愿意或准备去做，但被某事阻止了。
• needn't have + V3（主要是英式）：你做了，但其实没必要。比较 didn't need to + 动词：没必要，所以（通常）你没做。

• I could have gone to university, but I chose to work.

  我本来可以上大学，但我选择了工作。

• You could have told me the meeting was cancelled!

  会议取消了你也不告诉我一声！（轻微的抱怨）

• We couldn't have asked for better weather.

  天气好得不能再好了。

• I would have called you, but my phone died.

  我本来会给你打电话的，但我手机没电了。

• You needn't have cooked so much — there are only four of us.

  你其实不用做这么多菜的——我们只有四个人。（你已经做了）

• I didn't need to cook — we ate out.

  我不用做饭——我们出去吃了。（所以我没做饭）

• ✗She must has forgotten our meeting.

  ✓She must have forgotten our meeting.

  情态动词后面永远用 have。

• ✗You should have went to bed earlier.

  ✓You should have gone to bed earlier.

  have + 过去分词，不用一般过去时。

• ✗I should of told you earlier.

  ✓I should have told you earlier.

  should've 听起来像 “should of”，但其实是 have。

• ✗He can't have saw the message.

  ✓He can't have seen the message.

  can't have + 过去分词。

• ✗She should have been arrived by now.

  ✓She should have arrived by now.

  arrive 是主动的——不需要 been。

• ✗I must have left my keys at home, but I'm not sure.

  ✓I might have left my keys at home, but I'm not sure.

  不确定 → might / may / could have。