有must have been的用法么?虚拟语气里面?Do you still remember when we went to the Great Wall?I can't remember it well,but ____ sometime last autumn.A it must have beenB it could have been这题不能选A么,是没有这种用法还是意思

有must have been的用法么?虚拟语气里面?Do you still remember when we went to the Great Wall?I can't remember it well,but ____ sometime last autumn.A it must have beenB it could have been这题不能选A么,是没有这种用法还是意思
有must have been的用法么?虚拟语气里面?
Do you still remember when we went to the Great Wall?
I can't remember it well,but ____ sometime last autumn.
A it must have been
B it could have been
这题不能选A么,是没有这种用法还是意思有不对?
我看到语法书里有 主语+ would(could might should) +动词原型...没看到有must

有must have been的用法么?虚拟语气里面?Do you still remember when we went to the Great Wall?I can't remember it well,but ____ sometime last autumn.A it must have beenB it could have been这题不能选A么,是没有这种用法还是意思
是意思不对,这种用法有
前句说“记不清了”,若选A,意思是“一定在去年秋天的某个时候”,有些前后矛盾
选B,表示“应该是”
补充一下,这里不是虚拟语气,只是情态动词表推断

虚拟语气里面有must have been的用法。
这题只能选B
虚拟语气一直都被认为是英语学习中的一个难点，因此也便成为了各类考试的热点。现就虚拟语气的一些问题归纳如下，以帮助解决拟语气这个语法难点。
一、 动词wish后宾语从句中的虚拟语气
1． 用wish表示现在的祝愿和报歉。
其句子结构为：宾语从句的谓语be和were(was)，实义动词用过去式。...

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虚拟语气里面有must have been的用法。
这题只能选B
虚拟语气一直都被认为是英语学习中的一个难点，因此也便成为了各类考试的热点。现就虚拟语气的一些问题归纳如下，以帮助解决拟语气这个语法难点。
一、 动词wish后宾语从句中的虚拟语气
1． 用wish表示现在的祝愿和报歉。
其句子结构为：宾语从句的谓语be和were(was)，实义动词用过去式。例：I wish the were at home this time.
2． 用wish表示对过去事情的遗憾。其句子结构为：宾语从句的谓语用过去完成时，或could+现在完成时。例：I wish I hadn' t hurt him so much。
3． 用wish表示对将来事情的愿望。其句子结构为宾语从句的谓语为would/could/might+动词原形。例：I wish I might be able to come tomorrow 。
二、 用在一般虚拟条件句中的虚拟语气
（一） 表示与现在、过去、将来事实相反的假设
1． 与现在事实相反的假设。
其句子结构为：
从句：if+主语+动词的过去式（be变were）+其他
主句：主语+would(should, could, might)+动词原形+其他
例：If I were you, I would go with him.
2． 与过去事实相反的假设。
其句子结构为：
从句：If+主语+过去完成时+其他
主句：主语+should(would, could, might)+现在完成时+其他。例：If you had studied harder last term, you could have passed exam.
3．表示对将来事实实现的可能性不大的假设。
其句子结构为：
从句：If+主语+should (were to )+动词原形+其他
主句：主语+would (could, should, might)+动词原形
例：If he were to go tomorrow. He might tell you.
(二) 从句和主句要根据各自发所生的时间选用符合具体时间的虚拟语气形式
1． 从句表示过去，主句表示现在。
If they had stared the early morning yesterday, they would be here now.
2． 从句表示将来，主句表示过去。
If I were not to make a preparation for my experiment this afternoon, I would have gone to see the film with you last night。
3． 从句表示过去，主句表示将来。
If we hadn' t made adequate preparations, we shouldn' t dare to do the experiment next week。
4．从句表示将来，主句表示现在。
If we shouldn' t have an exam this afternoon. I would go
shopping now.
三、 可以引起与事实相反的方式状语从句，用虚拟语气 由as if、as though引起的与事实相反的句子，不论主句的谓语是现在时或者说过去时，其谓语表示的时间概念和句子结构，都基本上与wish后的宾语从句相同。例：
John pretends as if he didn' t know the thing at all, but in fact he knows it very well.(用过去式表示与现在事实相反的假设)
The old man looked at the picture, he felt as though he had gone back to time 20 years ago.（用过去完成式表示与过去相反的事实）
They talked and talked as if they would never meet again (would+动词原形，表示与将来事实相反)
四、在表示建议、命令、要求、忠告等动词的后面，其宾语从句的谓语用“should+动词原形”表示虚拟语气
常用的此类动词有：
表示“要求”的：ask, desire, request, demand, require, beg
表示“提议、劝告、建议”的：move, prpose, suggest, recommend, advise, vote
表示“决定、命令”的：decide, order
表示“主张”的：maintain, urge
表示“同意、坚持”的：consent, insist
例：The doctor suggested that he (should) try to lose his weight.
He insisted that we (should ) tell him the news.
上述动词的名词形式，demand, desire, requirment, advice, order,decision, recommendation, suggestion, 以及necessity, preference, plan, motion, idea等名词，其后的表语从句或同位语从句，也用“should+动词原形“表示虚拟语气。现代英语，特别是美国英语，常省去“should”，例：
The advice is that we (should) leave at once.
He idea that we (should)visit Great Wall was warmly
welcomed.
五、在“It is (was)+形容词（或过去分词）+that……”结构中，主语从句的谓语也用“should+原形动词“表虚拟语气
美国英语中省去should, 常用的形容词和过去分词有：
表示“要求”的：required, demanded, requested, desired, desirabl。
表示“建议”的：suggested, recommended,
表示“迫切、紧近、重要”的：imperative, urgent, necessary, essential, important, vital
表示“适当、较好”的：appropriate, advisable, better, preferable
表示“可能”的：probable, possible
表示“命令”的：ordered
例：It was necessary that we (should) make everything ready ahead of time.
It is required that nobody (should)smoke here.
六、由下列名词或短语引导，或含有某些词的从句中应用的虚拟语气
1．“Iest 以免、惟恐”引导的从句用“shuld+动词原形”。
He took a map with him lest he (should ) lose his wag there.
2．“whether不管、无论”引导的让步状语从句，有时用动词原形。
All things, whether you know or don' t know, exist in the world.
3．用“would rather/had rather' would just as soon"表示“宁愿、但愿”，后面的宾语从句谓语用过去式或动词原形表示对将来的要求，用过去时表示对现在的愿望，用过去完成时表示对过去做的事的懊悔。
Don' t live in the world, I would rather( I would just as
soon) you die.
I would rather you go tomorrow.
I would rather everything hadn' t happened in the past.
4．用“had hoped”表示原来希望做到而实际上未能实现的事情，其宾语从句的谓语用“would+动词原形”。
I had hoped that she would go to the U.S. and study there,
but she said she liked to stay in China.
5．在“It is（high/about）time+that”引导的定语从句中，定语从句的主谓语用一般过去时，偶尔也可以用would(或should)+动词原形，或had rather (would rather)+动词原形。
It is hihg (about)time that we left/should leave/ had better leave/had rather leave/ were leaving.(注意与“This is the first/second…time”后从句中用现在完成时的区别。
6．用“without/but for/in the absence of ”表示“要不是”，“如果没有”（相当于if it were not for…）表示条件时，句中一般用虚拟语气。（也可用陈述语气）
Without your help, I couldn' t finish my work on time.
In the absence of water and air, nothing could live
7．由“providing (that)/ provided (that)/on condition that/ in order that”引导的条件从句或目的从句，根据情况，可用虚拟语气。（有时也可用陈述语气）
They are willing surrender provided they are given free
passage.
8．在if引导的虚拟条件句中，若有were, had, should, 在书面语中可省去if ,将were等提到主语前，形成倒装。
Should there be a good film tomorrow. I would go to the
theatre with you.
Were it not for your help. I wouldn' t be succeed.

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