关于情态动词表推测的时态问题

①He must have left Beijing,（hasn't he?）

②A：Those tomatoes are huge!You must have watered them a lot!

B：Yes,I （did）.They ought to be ripe enough to pick by next Friday.

为什么①用现在完成时，②用一般过去时，②能不能用“Yes,I have.”？

①He must have left Beijing,（hasn't he 或 didn't he?）

②A：Those tomatoes are huge! You must have watered them a lot!

B：Yes, I （did 或 have）.They ought to be ripe enough to pick by next Friday.

must have done sth. ——用来表示对过去的推测。因为 must 表推测，只用于陈述句，不用于疑问句（包括附加问句）和否定句。如果去掉 must 的话，它包含两种情况，剩下的就是：一般过去时或者现在完成时。

我认为，网友这两句的简略回答，使用一般过去时或现在完成时，均可以。可惜，原句只给一个答案。

网友仔细看这两句，就知道为什么了：
It must have rained last night, didn't it?
You must have heard about it, haven't you? （或：didn't you?）

刘永科 - 教育出版集团英语总顾问 & 英语系列图书主编

擅长：语法理论,语言学,文化背景 | 采纳率 86% | 回答于 2021-09-15 18:21

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