初中虚拟语气知识点
初中虚拟语气知识点归纳
虚拟语气用来表示说话人的主观愿望或假想，所说的是一个条件，不一定是事实，或与事实相反。在条件句中的应用条件句可分为两类，一类为真实条件句，一类为非真实条件句。非真实条件句表示的是假设的或实际可能性不大的情况，故采用虚拟语气。
一、真实条件句：
真实条件句真实条件句用于陈述语气，假设的情况可能发生，其中if是如果的意思。
时态关系句型：
条件从句：一般现在时;
主句：shall/will+动词原形
如：If he comes, he will bring his violin.
注意：
1)在真实条件句中，主句不能用be going to表示将来，该用shall, will。
如： (错) If you leave now, you are never going to regret it.
(对) If you leave now, you will never regret it.
2)表示真理时，主句谓语动词便不用shall(will)+动词原形，而直接用一般现在时的动词形式。
二、非真实条件句：
非真实条件句表示的是假设的或实际可能性不大的情况，故采用虚拟语气。
1)时态：可以表示过去，现在和将来的情况。它的基本特点是时态退后。
a. 同现在事实相反的假设。
句型：从句：一般过去时;主句：should(would)+动词原形
如：If they were here, they would help you.
b.表示于过去事实相反的假设。
句型：条件从句：过去完成时;主句：should(would)have+过去分词
如：If she had worked harder, she would have succeeded.
The rice would not have been burnt if you had been more careful.
If my lawyer had been here last Saturday, he would have prevented me from going.
c.表示对将来的假想句型：
条件从句：一般过去时;主句：should+动词原形
从句： were+不定式;主句：would+动词原形 should+动词原形
如：If you succeeded, everything would be all right.
If you should succeed, everything would be all right.
If you were to succeed, everything would be all right.
三、混合条件句：
主句与从句的动作发生在不同的时间，这时主，从句谓语动词的虚拟语气形式因时间不同而不同，这叫做混合条件句。
如：
If you had asked him yesterday, you would know what to do now. (从句与过去事实相反，主句与现在事实相反。)
If it had rained last night (过去), it would be very cold today (现在).
比较if only与only if：
only if表示“只有”;if only则表示“如果……就好了”。If only也可用于陈述语气。
如：I wake up only if the alarm clock rings. 只有闹钟响了，我才会醒。
If only the alarm clock had rung. 当时闹钟响了，就好了。
If only he comes early. 但愿他早点回来。
It is(high) time that It is(high) time that 后面的从句谓语动词要用过去式或用should加动词原形，但should不可省略。
如：It is time that the children went to bed.
It is high time that the children should go to bed.
need“不必做”和“本不该做"”
didn't need to do表示：过去不必做某事，事实上也没做。
needn'thavedone表示：过去不必做某事，但事实上做了。
如：John went to the station with the car to meet Mary, so she didn't need to walk back home. 约翰开车去车站接玛丽，所以她不必步行回家了。
John went to the station with the car to meet Mary, so she needn't have walked back home. 约翰开车去车站接玛丽，所以她本不必步行回家了。(Mary步行回家，没有遇上John的车。)
特殊的虚拟语气词should 的用法：
1)It is demanded/necessary/a pity+that…结构中的主语从句的谓语动词要用should加动词原形，should可省略。
句型：
如：It is suggested that we(should) hold a meeting next week.
It is necessary that he(should) come to our meeting tomorrow.
2)在宾语从句中的应用在表示命令、建议、要求等一类动词后面的从句中。order, suggest, propose, require, demand, request, insist, command, insist+(should)do
如：I suggest that we(should) hold a meeting next week.
He insisted that he(should) be sent there.
注意：如suggest, insist不表示“建议”或“坚持要某人做某事时”，即它们用于其本意“暗示、表明”、“坚持认为”时，宾语从句用陈述语气。
如：The guard at gate insisted that everybody obey the rules.
判断改错：(错)You pale face suggests that you(should) be ill.
(对)Your pale face suggests that you are ill.
(错)I insisted that you(should) be wrong.
(对)I insisted that you were wrong.
3)在表语从句，同位语从句中的应用在suggestion, proposal, idea, plan, order, advice等名词后面的表语从句、同位语从句中要用虚拟语气，即(should)+动词原形。
如：My idea is that we(should) get more people to attend the conference.
I make a proposal that we(should) hold a meeting next week.
虚拟语气知识体系：
条件从句中的谓语动词形式主句中的谓语动词形式
与过去事实相反had+过去分词should/would+have+过去分词
与现在事实相反过去式should/would+动词原形
与将来事实相反1、过去式should/would+动词原形
2、should+动词原形should/would+动词原形
3、were to+动词原形should/would+动词原形
虚拟条件句的倒装：
虚拟条件句的从句部分如果含有were, should, 或had, 可将if省略，再把were, should或had移到从句句首，实行倒装。
如：Were they here now, they could help us.=If they were here now, they could help us.
Had you come earlier, you would have met him=If you had come earlier,
you would have met him.
Should it rain, the crops would be saved.=Were it to rain, the crops would
be saved.
注意：在虚拟语气的从句中，动词“be”的过去时态一律用“were”，不用was，即在从句中be用were代替。
如：If I were you, I would go to look for him. 如果我是你，就会去找他。
If he were here, everything would be all right. 如果他在这儿，一切都会好的。
初中虚拟语气知识点拓展：
一、条件状语从句
1、与现在事实相反若与现在事实相反，虚拟语气的条件从句的谓语用过去式(be通常用were)，主句谓语用“should (would, could, might)+动词原形”。如：If I were you, I would take an umbrella. 如果我是你，我会带把伞。(事实上我不可能是你)If I knew her number I could ring her up. 要是我知道她的电话号码，我就可以给她打电话了。(事实上我不知道)
2、与过去事实相反若与过去事实相反，从句：主语+had done ， 主句：主语+should/would/could/might+have done ，例如：If I'd left sooner，I'd have been on time. 要是我早点动身，我就准时到了。(但我动身太迟了)If I had got there earlier, I should/could have met her. 如果我早到那儿，我就会见到她。 (事实：去晚了)
3、与将来事实相反
从句：
①if+主语+were to do
②if+主语+did/were
③if+主语+should+do
主句：①主语+should/would/could/might+do
②主语+should/would/could/might+do
③主语+should/would/could/might+do
例如：If he went，would you go too? 如果他去，你也去吗?(大概他不会去)
If he should come here tomorrow, I would talk to him.
如果他明天来这儿的话，我就跟他谈谈。 (事实：来的可能性很小)
注意与说明：对于与将来事实相反的情形，请注意以下几点：
一是这里说的与将来事实相反，实为对将来情况的推测;
二是此用法中的条件从句谓语除用过去式外，有时也用“should+动词原形”(表示可能性极小，常译为“万一”)或“were to+动词原形”(表示与将来事实相反的假设);
三是当条件从句使用“should+动词原形”这样的谓语时，主句谓语除可用“should (would, could, might)+动词原形”这样的虚拟语气外，也可用陈述语气或祈使语气。
如：I should see him, I'll tell him. 万一我见到他，我就告诉他。
If it should rain tomorrow, don’t expect me. 万一明天下雨，就别等我了。
二、wish 后宾语从句
1、表示与现在事实相反的愿望，谓语动词用过去式 。
例如：
I wish I had your brains. 我希望我有你那样的头脑。(事实：我根本比不上你)
2、表示与过去事实相反的愿望，谓语动词：had+done
例如：I wish I had knownthe truth of the matter. 我希望我那时就知道这件事情的真相。(事实：那时还不知道)
3、表示将来难以实现的愿望，谓语动词：
should/would(情态动词) + 动词原形
I wish I should havea chance again. 我希望我还能有一次这样的机会。(事实：很难再有这样的机会了)
常见考法
The volleyball match will be put off if it___.
A. will rain
B. rains
C. rained
D. is rained
答案：B。真实条件句主句为将来时，从句用一般现在时。
There was plenty o ftime. She___.
A. mustn't have hurried
B. couldn't have hurried
C. must not hurry
D. needn't have hurried
答案：D。needn't havedone. 意为"本不必"，即已经做了某事，而时实际上不必要。 Mustn't have done用法不正确，对过去发生的事情进行否定性推断应为couldn't have done,“不可能已经”。must not do不可以(用于一般现在时)
典型例题：
_____to do the work, I should do it some other day.
A. If were I
B. I were
C. Were I
D. Was I
答案：C. 在虚拟条件状语中如果有were, should, had这三个词，通常将if省略，主语提前，变成were, should, had+主语的形式。
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