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基础语法知识-虚拟语气
英语中有三种不同的语气：陈述语气，祈使语气和虚拟语气。所谓的虚拟语气，可以理解为一种礼貌用语，比如需要别人按照你的意愿做一些事(建议、要求、命令)，或者是一些美好愿望，做出一些假设时，就用虚拟语气。
虚拟语气主要分为两大类，即should+do一类，和与事实相反两大类型。能基本掌握建议、命令、要求以及与事实相反类型中的条件状语句就基本够用了。
第一大类：（should） + v.(原形)
①表示“建议、愿望、命令”的相关句型
一坚持：insist
二命令：order，command
三建议：advise，suggest，propose，recommend
四要求：require，request，demand，desire（ask, urge, prefer）
跟在这些动词之后的宾语从句用（should）+ do结构
注意：当suggest作“表明”，insist作“坚持说、坚持认为”意思时，则不用虚拟语气。
②当以上词语发生词性变化时，与之相关的名词性从句也用虚拟语气
a. suggestion，proposal，order，request, advice, idea, plan etc.与之有关的表语从句、同位语从句、主语从句
b. It + be + adj./p.p/n. that从句
adj：important, necessary, essential, natural, strange
p.p: desired, suggested, proposed, recommended.
n.: a pity, a shame, a wonder, a must etc.
e.g. They insisted that we (should) go with them.
His proposal is that we (should) get rid of the bad habits.
It is suggested that the meeting (should) be put off till next week.
It is strange that he (should) have acted toward his parents like that.
My idea is that we (should) think it over before accepting it.
It is a pity that he (should) refuse to accept the offer.
③ It’s (high) time + that + should do/did … （(早该)到做某事的时间了）
e.g. It is (high) time (that) we should start out.
④ 目的状语从句中
在 in case, lest, for fear that, in order that, so that 等引导的状语从句中，动词用“could/should/ might/would等+v.(原形)”表示虚拟。
She called him lest he should go out.
They left early for fear that they would meet him.
第二大类：有时态变化的虚拟语气的结构 (与事实相反)
① 条件状语从句
从句 主句
与过去事实相反的假设 If +S. + had done S. + should/ would/ could/ might+ have done
与现在事实相反的假设 If +S. + did were S. + should/ would/ could/ might + do
与将来事实相反的假设 If +S. + did were to do should do S. + should/ would/ could/ might + do
e.g. If we had time now, we would read it again.
If I were you, I would work hard.
If he had taken my advice, he would have succeeded in the test.
If it should rain, the crops would be saved.
If it were to snow tomorrow, they would not go out.
注意： 虚拟条件句的特殊情况
(1). 混合/错综型虚拟语气
当条件状语从句表示的行为和主句表示的行为所发生的时间不一致时，称为‘错综条件句’，动词的形式要根据它所表示的时间作出相应的调整。
If you had followed my advice, you would be better now. (从句说的是过去，主句是现在)
If I were you, I would have taken his advice. (从句是现在，主句是过去)
（2）省略if的虚拟语气
如果从句中含有were/ should/ had时，则可以把这三个词置于句首，省略if.采用倒装语序。
If it should happen, what would you do
→Should it happen, what would you do
If he had recognized me, he would have come over.
→Had he recognized me, he would have come over.
(3) 含蓄虚拟条件句
a. 有时候假设的情况不以if引导的条件从句形式表现出来，而是通过一个介词短语，连词或其他形式表示。常用的词或短语有：without, with, but for(要是没有), otherwise, or, but等。
Without your help (=If we had not had your help), we could not have succeeded.
But for electricity (=If there were no electricity, there would be no modern industry.
He felt very tired yesterday, or/ otherwise he would have attended the party.
b. 用分词短语、名词短语代替条件状语从句
e.g. Born in better times (=if he had been born in better times), he would have been a scholar.
Failing this time (=if you failed this time), what would you do
A few hours earlier (=if you had come a few hours earlier), you would have been able to meet the famous writer.
②与主句谓语动词有先后关系
a. wish+ O. clause
> S. + had done/ could have done （从句先于wish发生）
> S. + did/were （与wish同时发生）
> S. + would/should/could/might+do（从句后于wish同时发生）
（how I wish = if only 后面所跟的宾语从句时态用法与之相同）
e.g. I wish (that) I were a bird and could fly freely in the sky.
I wish (that) I had met the film star yesterday.
How I wish I were you.
If only I were a flying bird! = How I wish I were a flying bird.
b. would rather, would prefer 等表示希望或婉转责备的动词后的宾语从句的动词用虚拟语气。
从句谓语动词用did/were 表示对现在或将来的虚拟
从句谓语动词用had done 表示对过去的虚拟
e.g. I would rather he came next Saturday.
I would prefer you had seen the film yesterday.
I would rather they didn’t hear of the news.
c. as if/as though 引导的从句与事实相反；even if / even though 引导的让步状语从句与事实相反时，从句用虚拟语气,其形式与if从句在虚拟语气中的形式相同
主语+as if/ though +主语+一般过去时（从句的动作与主句同时发生）
主语+as if/ though +主语+would/could+动词原形（从句的动作相对主句来说在将来发生）
主语+as if/ though +主语+过去完成时（从句的动作先发生于主句动作之前）
e.g. When the pencil is partly in a glass of water, it looks as if it were broken.
The two strangers talked as if they had been friends for years.
Even if I were rich, I would work.
d. 动词hope, intend, mean, plan, want, think等词用过去完成的形式，表示的意思为“本想，本打算，本认为”
He had meant to buy the furniture last week, but it rained.
（他上周本打算去买那件家具，但却下雨了）
基础语法知识--名词性从句
1. 基本概念
名词性从句指在句子中起名词作用的句子。名词性从句的功能相当于名词词组，它在符合剧中能够担任主语、宾语、表语或同位语，根据它在句子中不同的语法功能，被分为主语从句、宾语从句、表语从句和同位语从句四大类。
2. 名词性从句的引导词
连接词 语义 在从句中的作用
连接词 that 无 不充当成分
whether/if 是否 不充当成分
as if/ as though（只连接表从） 似乎 不充当成分
连接 代词 what(ever) 什么；…的事/东西；多么 充当主、宾、表、定
who(ever)/whomever 谁 充当主、宾、表
which(ever) 哪一个 充当主、宾、表、定
whose 谁的 充当定语
连接 副词 when(ever) 什么时候 充当状语
where(ever) 什么地方 充当状语
why 为什么 充当状语
how(ever) 怎么; 多么 充当状语
because（只连接表从） 因为 充当状语
3. 主语从句
概念：作句子主语的从句称为主语从句，通常位于谓语动词之前。
e.g. What he wants to tell usis not clear.
Who will win the match is still unknown.
有时为了避免头重脚轻，常用it作形式主语，真正的主语放后面。it作形式主语的常用句型
（1）It + be + 名词 + that从句
It is a fact that 事实是
It is an honour that 非常荣幸
It is common knowledge that …是常识
It is a pity that 遗憾……
（2）It + be + 动词的过去分词+ that从句:
It is said that 据说
It is reported that 据报道
It has been proved that 已经证明
It is believed that … 人们认为
It is supposed that… 据猜测
（3）It + 不及物动词（vi） + that 从句：
It seems that 似乎
It happened that 碰巧
It appears that 似乎
It occurred to sb. that 某人突然想到
（4）It + be + 形容词 + that从句
It is natural that… 很自然…
It is strange that… 奇怪的是…
注意:在主语从句中用来表示惊奇、不相信、惋惜、理应如此等语气时，谓语动词要用虚拟语气“(should) +do”，常用的句型有： It is necessary (important, natural, strange, etc.) that …
It is suggested (requested, proposed, desired, etc.) that…
4. 表语从句
概念：位于系动词之后的句子叫作表语从句。（系动词参考知识点一、3）
表语从句特殊引导词有as if/ though, because
常用句型：It looks as if…../ It seems as if…..
why, because都可以引导表语从句，但why强调结果，because强调原因
注意：当主语是reason时，表语从句要用that引导而不能用because。
e.g. The reason why he was late was that he missed the train.
5. 宾语从句
1）概念：在句子中作宾语的从句叫宾语从句。通常位于及物动词或介词之后。另外部分表情绪的形容词后也可接宾语从句。
e.g. I’m glad that you’ve passed the exam.
注意：由that引导的宾语从句，第一个引导词that可以省略。
2）宾语从句中的时态呼应。
当主句动词是现在时，从句根据自身的句子情况，而使用不同时态。例如：
I know (that) he studies English every day. （从句用一般现在时）
I know (that) he studied English last term. （从句用一般过去时）
I know (that) he will study English next year. （从句用一般将来时）
I know (that) he has studied English since 1998. （从句用现在完成时）
当主句动词是过去时态（could, would除外），从句则要用相应的过去时态，如一般过去时，过去进行时，过去将来时等；当从句表示的是客观真理，科学原理，自然现象，则从句仍用现在时态。例如：
The teacher told us that Tom had left us for America．
6. 同位语从句
概念：同位语从句说明其前面名词的具体内容，位于名词之后，通常由that或whether引导。
常跟同位语从句的抽象名词有belief、advice、demand、doubt（怀疑）、possibility、thought、proposal、fact、hope、idea、information、message、news、problem、promise、question、request、suggestion、truth、wish、word等。例如：
The news that we won the game is exciting.
I have no idea when he will come back home.
The thought came to him that Mary had probably fallen ill.
同位语从句与定语从句的区别：
(1) 定语从句中的that既代替先行词，同时也在从句中作主语或宾语，而同位语从句中的that是连词，只起连接主句与从句的作用，不充当句中任何成分。
(2) 定语从句是形容词性的，其功能是修饰先行词，对先行词加以限定，描述性质或特征；同位语从句是名词性的，其功能是对名词进行补充说明。例如：
1) The news that he told me is that Tom would go abroad next year.
（他告诉我的消息是汤姆明年将出国。）
（第一个that引导定语从句，指代the news,在从句中充当told的宾语。）
2)The news that Tom would go abroad is told by him.（汤姆将出国的消息是他讲的。）
（that引导同位语从句，在从句中不充当成分也没有语义。）
7. 考点归纳
1）what/that的区分
名词性从句中，what属于连接代词，在从句中充当主、宾或表语，译为“什么”或“…的事/东西”。that属于连接词，既不充当任何句子成分也没有语义，只起连接从句的作用。
e.g. What he wants is a book. (what引导主语从句，意为“…的东西”)
That he wants go there is obvious. (that引导主语从句，无语义)
2）which/what的区分
what通常意为“什么”，表泛指；which意为“哪一个”，一般有选择范围。
e.g. I can’t imagine what made him act like that. (我无法想象什么让他变成那样。)
Would you mind telling me which language your friend speaks, English or French (which有选择范围)
3）who/whoever的区分
who的意思是“谁”，含有疑问意义，带有唯一性。whoever是“任何…人”“无论谁”，不含有疑问意味，带有任意性。
e.g. It was a matter of who would take the position. (问题是谁将接替这个位置。)
Whoever has helped to save the drowning girl is worth praising. (无论谁救了这个溺水的女孩都值得被称赞。)
4）只用whether，不用if情况
置于句首的主语从句中
Whether we will hold a party in the open air tomorrow depends on the weather.
表语从句、同位语从句中
The question is whether he should do it.
介词后的宾语从句中
We’re worried about whether he is safe.
与or not连接
I don’t know whether or not he is well.
后面直接跟to do
I haven’t decided whether to go there
8. 名词性从句中的虚拟语气
1）主语从句
It is suggested/ advised/ proposed/ recommended/ ordered…that + (should) + do
It is necessary /essential /important / natural / advisable / strange / surprising… that + (should) + do
It is a pity /a shame / no wonder… that + (should) +do
2) 宾语从句
在以下动词后接的宾语从句中，谓语动词应用(should) + do. 记住以下口诀：
1坚持：insist (坚持要求)
2命令：command, order
4建议：suggest, advise, propose, recommend
4要求：require, desire, request, demand
e.g. He demanded that we (should) arrive on time.
We required that the work (should) be done right now.
3) 表语从句和同位语从句
作 order /suggestion / advice / proposal / recommendation /requirement/request / demand /plan / idea 等名词后的表语从句和同位语从句中谓语要用“(should)＋动词原形”。
e.g. My advice is that the meeting (should) be put off.
We all agree to his suggestion that we (should) start early.
倒装句分为部分倒装、完全倒装和形式倒装三种类型。
（1）部分倒装
部分倒装句的掌握，在于一般疑问句的语序理解。掌握了一般疑问句，就基本掌握了部分倒装句的套路。所以在讲解部分倒装之前，我们来回顾一下一般疑问句的语序是怎么样的。 请把下列句子转变为一般疑问句：
1) She is a clever student.
2) She can speak English and France.
3) She also speaks Spanish.
4) Sha has learnt Spanish for 3 years.
5) She will learn to speak Chinese next year.
我们是这样来变化的：有助动词(be, have/has/had, will)或情态动词(can, could, may...）时，直接提前助动词或情态动词，没有助动词时，添加助动词do/does/did,并还原动词。所以这五个句子的一般疑问句分别如下：
1) Is she a clever student
2) Can she speak English and France
3) Does she also speak Spanish
4) Has she learnt Spanish for 3 years
5) Will she learn to speak Chinese next year
部分倒装句的语序顺序遵循一般疑问句的语序顺序。
部分倒装共有五种类型，分别为：
① 当否定词或否定短语置于句首时，后面的句子需要用部分倒装。如hardly, rarely, seldom, scarcely, barely, never, not, few, little, neither, nor, not only, hardly…when, in no case, by no means, no sooner…than等
e.g.
正常语序：The written examination probably wasn't known until the 19th century.
倒装语序：Not until the 19th century was the written examination probably known. (有until的句子，倒装时要把not 和until一起放到句首)
正常语序：He had not only taken away everything, but also his German citizenship.
倒装语序：Not only had he taken away everything, but also his German citizenship.
② only+状语 置于句首时，主句部分需要用部分倒装
e.g.
正常语序：I realized the value of reading aloud every moring only then.
Only then did I realize the value of reading aloud every morning.'
正常语序：We can avoid misunderstanding each other only by means of talking.
Only by means of talking can we avoid misunderstanding each other.
③ “so /such +表语/状语 + that从句”结构中的so 或such引导的表语/状语放在句首时。
e.g.
正常语序：She was so frightened in the darkness that she didn't dare to move at all.
So frightened was she in the darkness that she didn’t dare to move at all.
正常语序：He is such a lovely child that all of us love him.
Such a lovely child is he that all of us love him.
④ 在no sooner…than, hardly…when, not only…but also句型中, 前面的句子要部分倒装。
e.g.
正常语序：I had no sooner reached the station than the train left.
No sooner had I reached the station than the train left.
正常语序：I had hardly reached the station when the train left.
Hardly had I reached the station when the train left.
⑤ so, as, neither, nor, no more 表示前面的情况也适合于另一人或物时。
e.g. Tom can speak French. So can Jack.
If you won’t go, neither will I.
（2）完全倒装
①为了平衡句子结构的需要,或为了强调状语(常为介词短语)，或为了使上下文紧密衔接时，将状语提前。
e.g. They arrived at a farmhouse, in front of which sat a small boy.
Nearby were the canoes in which they had come to the island.
② 方位词in, out, there, here, inside, outside, up, down, away, off, downstairs, upstairs等以及now, then置于句首时，谓语动词常用be, come, go, lie, run等，并且句子的主语是名词。为以示强调或为了使情景更生动, 要全部倒装。
e.g. Away flew the bird which I bought yesterday.
Now comes your turn to sweep the floor.
③ here/ there句式，采用完全倒装形式
e.g. There is an experienced teacher and many lovely students in the classroom.
There lay a winding brook in front of an old house.
④ such和be连用作表语时，也常用倒装语序。（全部倒装）
e.g. Such was not his intention.
Such are the facts.
（3）形式倒装
当as, though 引导让步状语从句时，从句需采用形式倒装，即从句中的表语、状语、动词原形置于句首，若表语时单数名词，前置时要省略冠词。
e.g. Proud as they are, they are afraid to see us.
Child as he is, he knows a lot.
Try hard as they would, they could not lift the box.

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