could have down除了虚拟语气还有什么用法They could have gone for a holiday as the house seemed empty.这句话是对的，但我感觉这里不是虚拟呢？

could have down除了虚拟语气还有什么用法They could have gone for a holiday as the house seemed empty.这句话是对的，但我感觉这里不是虚拟呢？
could have down除了虚拟语气还有什么用法
They could have gone for a holiday as the house seemed empty.这句话是对的，但我感觉这里不是虚拟呢？

could have down除了虚拟语气还有什么用法They could have gone for a holiday as the house seemed empty.这句话是对的，但我感觉这里不是虚拟呢？
could have done除了虚拟语气还有什么用法?
Answer:除了表虚拟还可以表推测
注:虚拟和推测是两种不同的概念
虚拟--是对已经存在的事实做出的相反假设
推测--只是对事实的推理,其结果可能与事实相符也可能不符.
一
推测用法
Can/could have done 表对过去发生事情的推测一般用在否定句和疑问句中.
如:LZ所例此句
They could have gone for a holiday as the house seemed empty
这里"could have done"就是表示对过去的推测.
译为:他们可能去度假了
如果要表虚拟,那么意思为
他们本可以去度假 (显然前后不合逻辑)
例:
1)Can/Could he have passed the exam?他可能通过了考试吗?
2)I think that he couldn’t/can't have gone abroad,for I saw him just now.我认为他不可能出国了,因为我刚才还看见他了.
二.
虚拟用法:
could (不能用 can) have done 表示“过去本能够做某事却未做.
注意：其否定形式 couldn't have done 没有虚拟语气的用法 只能表推测,相当于 can't have done,意为：“过去不可能做了某事
例:
You could have done it better.
你本可以把这件事做得更好.(事实上做的不是非常完美)
If you still feel confused,leave a message please

没有别的用法了
这里表示推测，不是固定用法，could意为可能

没了

是could have down还是could have done？