非真实条件句,表示与现在事实相反的情况,条件从句中的谓语动词为什么要用动词的过去式?

虚拟就是假设的意思,也就是还没有发生的事情才用虚拟,将来时就是没有发生的事情,只能假设它发生,所以用虚拟.
你把问题想的太复杂了吧?你不要管是不是与现实违背什么的,只要是假设,就可以用虚拟,虚拟就是假设

1、i won't succeed if only i worked hard.要虚拟语气吧?

前一句中IF表条件,假设的意思.有现实依据用WAS后句省略IF为虚拟语气所以用WERE

虚礼语气
1.主语从句中的虚拟语气 主语从句中的虚拟语气主要取决于某些形容词和过去分词,用来表示建议、命令、要求、惊异和失望等.其形式为：（should）+ 动词原形.常这样用的形容词有：appropriate 适当的 advisable 适当的,合理的 better 较好的 desirable 理想的 essential 精华的 imperative 迫切的 important 重要的 insistent 坚持的 natural 自然的 necessary 必要的
preferable 优越的,较好的 strange 奇怪的 urgent 紧迫的 vital 极其重要的 过去分词有：desired,demanded,ordered,requested,suggested,recommended,required 等.例如：It is essential that you （should） win the voters‘ hearts.
赢得选民的心是绝对必要的.It was suggested that he （should） join the club activities.
有人提议他应该参加俱乐部的活动.2.表语从句和同位语从句中的虚拟语气 在表示建议、命令、主张、目的和愿望等名词后面的表语从句和同位语从句中谓语动词要求使用虚拟语气.其形式为：（should）+ 动词原形.常这样用的名词有：resolution 决心,决议 pray 恳求 decision 决议 motion 提议 suggestion 建议 preference 选择 proposal 提议 advice 劝告 recommendation 推荐 desire 愿望 demand 要求 requirement 要求 order 命令 necessity 必要性 request 要求 idea 主意、想法 例如：He gave orders that the guests （should） be hospitably entertained.
他下令热情款待这些客人.His proposal is that we （should） get rid of the bad habits.
他提议我们应该摈弃这些不良习性.
……

一：If the steamer should have left port at noon,it will be passing through the canal now.这句是混合虚拟~前面半句是对过去的虚拟~后面半句是对现在的虚拟~其中now就是现在的标志~
二：should表虚拟~
三：should也表虚拟~
四：desirable也是虚拟的标志语~It is desirable that 后面就要用虚拟~这类词还有很多necessary,essential之类~语法书上有的~把他们记住就行了~

是的,主语是a heavy snow ,可be 动词用了were,明显是非真实条件句
如果说话人（不是读者）觉得难以实现,比较渺茫,他就可以用虚拟条件句

一、if 和 unless 根据说话者的言外之意,可以引导两种语气的条件句：
1.真实条件句
She will play the piano only if she is paid.只有付给她报酬,她才愿意演奏钢琴.（付给报酬是可能的）
Unless he studies hard,he will never pass the examination.
他如果不努力学习,就永远不能考及格.（其实他就是不努力学习）
2.虚拟条件句
If I were to go,I would be late.若我去,就要迟到.（根本就把打算去）
I should go unless it rained.如果不下雨我就去.（雨没有停止的可能）
二、unless = if not,因此无论是真实的还是虚拟的,后者可以用来取代前者,如上面句子的改写：
If he doesn't study hard,he will never pass the examination.
I should go if it didn't rain.
三、but that 和 but for 意思是“若不是”,只用于虚拟语气,如上面虚拟条件句的进一步改写：
I should go but that it will rained.（注意：因为确实要下雨,but 从句本身不虚拟,但主句需要虚拟.）
I should go but for raining.
另如下面例句的反向改写(注意以下各句从句的时态)：
They would have resisted but that they lacked courage.如果不是缺乏勇气她们会抵抗的.
They would have resisted unless they had lacked courage.
They would have resisted if they had not lacked courage.
四、except that / except for / except on condition that 是对主句细节的修正,只用于真实语气,如：
She will play the piano only if she is paid.可以改写为：
She will play the piano except that she will be paid.
She will play the piano except on condition that she will be paid.

When we find ourselves entertaining an opinion about which there is a feeling that even to enquire into it would be absurd,unnecessary,undesirable,or wicked-we may know that that opinion is a non-rational one.
答：主句：we may know that that opinion is a non-rational one.
时间状语从句：when we find ourselves entertaining an opinion （about which-定语从句）
定语从句：about which there is a feeling (that-同位语从句）
同位语从句：that even to enquire into it would be absurd,unnecessary,undesirable,or wicked
译：当我们发现自己能够有一种,对这种观念感觉即使去探究一下都是荒唐的、不必要的、不合乎需要的或是不道德的--那么我们或许就知道,那个观念是不合理的.
这里的when也可以理解成if,是真实的条件句.
同位语从句中主句用的是虚拟语气,隐含了一个虚拟条件

你好 很高兴为你解答 请看网址http://baike.baidu.com/view/26751.htm#1 http://baike.baidu.com/view/630435.htm
真实条件句实际上就是条件状语从句,这个是真实的,有可能发生
但虚拟语气则是不可能实现的,例如：如果我有100万,我将周游世界,这就是虚拟语气,又叫非真实条件句 详细组成看我给的网址 谢谢

条件状语从句相当于真实条件句,即你要表述的句子是真实的.
虚拟条件句=非真实条件句,即描述的事实不是真实的,是虚拟的,或做出的假设是不切实际的,发生几率非常小的.
例如:If i rains tomorrow,i won't go to the library.(天气预报说明天很有可能下雨,而且现在天空也是乌云密布的的,明天下雨的几率实在是太大了,所以用条件状语从句,而不用虚拟语气)
If it should rain tomorrow,i wouldn't hang out.(天气预报明天为晴,即下雨的几率很小,而且现在天空也是万里无云的,所以要用虚拟语气,表示对将来的一种假设,一种发生几率很小的假设)

答：从形式和意义两方面去判断.
一、形式
虚拟条件句中的谓语动词必定是过去时态.主句必定是would+ do / have done 形式.（would根据人称和意思,可改用should （第一人称）,和could (能）,might(可能））
具体：
if从句 主句
与现在情况相反的假设：did would +V.
与过去情况相反的假设：had done whould have done
与将来情况很可能相反的假设：did/ were to+V./ should +V.would +V.
注：be动词用律用were
二、从意义上去判断.
象If I were you,I would do sth.很明显是假设的,因为我怎么可能是你呢?
主要还是要从形式上去判断.
如有人说：如果我有10万元,我就买一辆新车.这是很难判断这是虚拟语气的句子,还是真实的条件句.但是：
If I have 10,000 yuan,I will buy a new car.这就是陈述语气.
而：If I had 10,000 yun,I would buy a new car.就明显是虚拟语气.

非真实条件句（我说成是虚拟语气）分别分成对过去,现在,将来的虚拟
条件从句 主句
过去 had +过去分词 would（should）+过去分词
现在 过去式（be用were） would（should)+动词原形
将来 过去式/should /were to+动词原形 同上
这个表格记住就明白虚拟语气怎么使用了,虚拟语气顾名思义是不可能发生的
比如If I were you,I .我不可能是你所以用了对现在的虚拟
而真实句式表示有可能发生的,比如If he comes home,please call me at once.
大概就是这些,如果还有不懂,可以问我

ut for =withou
第二句是条件句的变形.实际上这也是个固定句型：祈使句+or/and 句子(这句子常一般将来时,我看第二句的includes 要改成will include)
这里的祈使句可以换成一个条件句：If you read Homer,and .
又如：Step further,and I will fire如果你再走远点,我就开枪了.
Stop,or I will fire停下来,否则我开枪了.

是英语方面的问题吗?
两者并不等同的
有交叉和并列
呵呵……不过还是回答你好了
下面是一些资料,希望对你有帮助.
一、概念
[Subjunctive Mood]
中文译作"虚拟语气".它是一种动词形式,表示说话人的某种假设、愿望、怀疑、猜测、建议等含义.
二、语法结构
1.if结构（非真实条件句——表示的是假设的或实际可能性不大的情况）
与..事实相反 If从句 主句
过去 Had done Would* have done
现在 Were/did Would* do
将来 Should do/were/were to do Would* do
例句：If there hadn’t been much rain in spring, we would have had a good harvest now. [过去]
If he smoked less, his cough might be well soon. [现在]
If the lecturer should be late, you would have to make a speech first. [将来]
备注：
（1）上表中’*’,would都可转换为should、could、might.
（2) 如果为时间错综句的话,左右两栏可互相搭配,排列组合.
例句：
He would still be alive today if he hadn’t taken that drug.
[与现在事实相反] [与过去事实相反]
(3) if可转换为其他形式
例句：Without your advice, our meeting wouldn’t have been so successfully. [过去]
（=>可转换为：If there hadn’t been your advice, we …）
Your notes are almost illegible (难以辨认的). Notes typed out would be a lot easier to read. [将来]
(=> 可转换为：If the notes had been typed out, it would be a lot easier to read.)
I should have gone to see Dr. Smith and he might have cured me of the disease.[过去]
(=> 可转换为：If he have gone to see Dr. Smith, he ..)
2、wish结构
与..事实相反
过去 Had done
现在 Were/did
将来 Would
备注：可转换为其他形式.
例句：He talks as if (好像) he had done all the work himself. [过去]
I wish I were a bird.
I wish he handn' done that.
I wish I would be rich in the future.
3、should结构
从句中用“should + 动词原形”构成.而且should可以省去.用于此结构的动词有：advise, direct, agree, ask, demand, decide, desire, insist, order, prefer, propose, request, suggest,intend等.
例句：The teacher suggest he (should) read English aloud.
注意：当insist表示“坚持认为”、suggest表示“表明,显示”时,不用虚拟语气.
例句：The look on his face suggested that he was quite satisfied with what I had done for him.
He insisted that he was honest.
4、would rather ＋从句
在这种结构中,从句的谓语动词用过去形式表示虚拟.
例句：I would rather you did this instead of me.
5、主语从句中的虚拟语气
1）It be + 形容词 + that ．．．（should）．．．
用于该句型的形容词是：necessary, good, important, right, wrong, better, natural, proper, funny,
strange, surprising ．
一些名词也可以用于 在该结构中.如：a pity, no wonder．．．．
2）It be + 过去分词 + that ．．．（should）．．．．
用于该结构中的过去分词是表示“建议、请求、命令”等词的过去分词.如：desired, suggested, requested,
ordered, proposed等.
3）It is time（about time, high time）that ．．．（过去式动词形式或should＋动词原形）．．．．
It is high time I went home now. = It is high time I should go home now.
6、表语从句、同位语从句中的虚拟语气
在suggestion, proposal, order, plan, idea, advice, decision等需要有内涵的名词后面的表语从句、同
位语从句中,要使用虚拟语气.其谓语动词应用：should＋原形动词.另外连接从句的that不能省
略.
例：My suggestion is that we should go there at once.
What do you think of his proposal that we should put on a play at the English evening?
三、使用范围及判断
1、虚拟语气表示一种不能实现的假设.该语法主要用于if条件状语从句.也可用于主语从句、表语从句、宾语从句等.
2、if条件状语从句中虚拟语气的判断
判断是真实条件句还是非真实条件句.只有在非真实条件句中才使用虚拟语气.通过句子意思,看假设的条件是否能够实现,能够实现是真实条件句,不能使用虚拟语气；假设的条件不能实现则是非真实条件句,要用虚拟语气.
判断这个假设是与哪个事实相反.通常有三种情况：①与过去事实相反.②与现在事实相反.③与将来事实可能相反.
3、“后退一步法”
后退一步法是指在准确地判断了该句与哪一事实相反后,按虚拟语气的后退一步法处理从句谓语动词的时态.即：在非 真实条件状语从句中,谓语动词按正常情况“后退一步”.也就是：
1）与过去事实相反,在从句中用过去完成时形式表示.
2）与现在事实相反,在从句中用过去一般时形式表示.
3）与将来事实可能相反,在从句中用过去将来时形式表示.
主句中则用情态动词would, should, could 等加一个与从句一致的动词形式.
例：If I had come her yesterday, I would have seen him.
If I were a teacher, I would be strict with my students.
If it should snow tomorrow, they couldn’t go out.
四、注意事项
1.if条件句中如有were, should, had,可以省去if,并使用倒装语序.
2、在现代英语中if条件状与从句中的谓语动词如果是be其过去形式一般用were.
3、wish 后面宾语从句中的虚拟语气,按“后退一步法”处理从句的谓语动词.注意：与哪个事实相反,不能以主句的时态为判断依据,而是根据从句的意义判断

)when we are tempted to say that general truch is so obvious that it will be absund even to question it...( that 后是宾从,含 so...that 句型 ,第二个that后是结果状语从句）.真实条件句
it would be quite wrong to attribute all opinions-even political opinions-to-self-interest（ 含attribute ...to ...句型,第一个to 后是本句真实主语.
but it would be equally wrong to deny that this is one potent factor（和第二句结构一致,deny后+ 宾语从句）

1. 条件状语从句通常由连词if引导，意为“如果，假如”，主句不能用be going to 表示将来，而应该用shall或will。 例如： If I’m free tomorrow, I’ll go with you. 如果我明天有空，我将会和你一起去。 2. if引导的条件状语从句，主句用一般将来时，从句则用一般现在时，即“主将从现”。 例如： If it is sunny tomorrow,...

1：But for his help,we would be working now.
要不是他的帮助,我们还会在工作呢.还在工作就应该表示正在工作,所以用be+动名词
2：Without your instruction,I would not have made such great progress.
要是没有你的指导,我不会取得如此大的进步.
3：We didn't know his telephone number,otherwise we would have telephoned him.
我们不知道他的电话号码,否则我们就会给他打电话.
第二第三句都是事实上这个是和过去的真实情况相反的,所以我们用虚拟语气,同时它又是表示过去的时间的所以我们用would have done的形式

用were
I wish he were here.
If he were here tomorrow,the earth would stop moving.
但是：it is (about / high ) time she / he was here.(这里不能用were)

1``At last the meeting suggested all the sidespresent___to develop the area together. A.allowed B.should allow C.were allowed D.be allowed```````D suggest表建议时其后的宾丛要用虚拟语气!即 should+动原 ...