高中英语疑问

Question

It wasn't a good idea to throw the bottle out of the window.
It____ hit somebody.
A.would have B.should have C.could have D.must have
1\首先为何要用虚拟?（ABCD都用了虚拟）
2\为什么用could have不用would have,有什么区别？
3\ could have 与might have 意思同吗？这可以用 might have 吗？
亟待帮助，感激！

Answer 1

这里考查的不是虚拟语气，是情态动词+have done 表示对过去的情况进行推测。
could have done 对过去的事情进行肯定的推测，意思是“也许会...”
would have done只用在虚拟语气的主句中，所以这里不对。
should have done表示过去本应该做某事而实际上没做，含有责备的意思。
如：You couldn't remember his address.You should have written down the address for him.
might have done可以表示对过去的事情的肯定推测，但是语气比could较弱。
下面给你一份资料供你参考
.对过去情况的推测，用“情态动词 + have +过去分词”。
（1）It must / may / might / could have rained last night .The ground is wet.
地湿了，昨晚肯定/可能/也许下雨了。
（2）The door was locked. He can ( could ) not / may ( might ) not have been at home .
门锁着，他不可能/可能不在家。
（3）Can / Could he have gotten the book？
难道他找到书了吗？
注：情态动词 should /ought to表推测时，意为“想必会，理应……”
与“have +过去分词”连用时，意为“本应该做某事却没做”。例如：
（4）It’s seven o’clock. Jack should/ought to be here at any moment.
现在七点钟了，杰克理应随时到达。（推测）
（5）She should / ought to have attended your birthday party, but she had to look after her mother in hospital.
她本该出席你的生日晚会的，可是她得在医院照顾她妈妈。
（6）Tom should not /ought not to have told me your secret, but he meant no harm. 汤姆本不该告诉我你的秘密，可是他并无恶意。

Answer 2

首先，谁告你它用虚拟了。这里考察情态动词的语气强烈程度和所偏向的意思。must语气太强，可当作一定会发生，不符。这里不用虚拟语气。A通常表示“应该”发生的情况。should后跟完成时表示与事实相反的情况。同时根据语意，这里应该填“可能”发生的情况。might的语气比could相对较弱。而这里说话人有种警告的意思，也不太好