省略句的概念：

在英语语言中，为了使语言简洁明了，重点突出或上下文紧密相连，可以省去某些句子成分而保持句子愿意不变，这种语言现象称之为省略。

简单句中的省略：

1、省略主语：
1）祈使句中的主语通常被省略。
如：(You) Open the door, please. 请开一下门。
2）其它省略主语多限于现成的说法。
如：（I）Thank you for your help. 谢谢你的帮助。 
        （It）Doesn't matter. 没关系。
2、省略主谓语或主谓语的一部分：
如：（There is）No smoking. 禁止抽烟
        （Is there）anything else? 还有其他事吗？
        （You come）This way please. 请这边走。
        （Will you）Have a smoke? 抽烟吗？
3、省略宾语：
如：—Do you know Mr. Li? 你认识李先生吗？
        —I don't know (him.) 我不认识他
4、省略表语：
如：—Are you thirsty? 你30岁了吗？　
        —Yes, I am (thirsty). 是的，我是。
5、同时省略几个成分：
如：—Are you feeling better now? 你觉得好些了吗？
        —(I am feeling) Much better (now) 好多了。
       (I wish)Good luck(to you). 祝你好运/祝你顺利。

省略句在复合句中的应用：

一、并列复合句中的省略：
并列句中后边的分句可以省略与前边分句中相同的成分。
如：The boy picked up a coin in the road and (the boy) handed it to a policeman. 
        这个男孩在马路上拾起一枚硬币并把他交给了警察。
        Your advice made me happy but(your advice made) Tom angry. 你的建议使我高兴但使汤姆生气。
        Tom must have been playing basketball and Mary(must have been) doing her homework.
        汤姆肯定一直在打篮球，玛丽一直在写作业。
        Gao Xiumin was born in 1959 and Fu Biao(was born) in 1963. 高秀敏出生于1959年，傅彪出生于1963年。

二、主从复合句中的省略：
1、状语从句中的省略：一般说来省略现象多出现在下列五种状语从句中：
1）由when,while,as,before,after,till,until,once等引导的时间状语从句；
2）由whether,if,unless等引导的条件状语从句；
3）由though,although,evenif,whatever等引导的让步状语从句；
4）由as,than等引导的比较状语从句；
5）由as,asif,asthough等引导的方式状语从句。

上述状语从句在省略时应遵循下面原则：
当状语从句的主语与主句的主语一致时，可以省略状语从句的主语和系动词be，这时从句中可出现如下结构：
连词（as,as if, once）+名词；
连词（though, whether, when）+形容词；
连词(whether, as if, while)+介词短语；
连词(when, while, though)+现在分词；
连词(when, if, even if, unless, once, until, than, as)+过去分词；
连词(as if,as though)+不定式。
如：Once(he was) a worker, Pang Long now becomes a famous singer.
        庞龙曾经是个工人，现在变成一位著名的歌手。 
        Work hard when(you are) young, or you'll regret. 趁年轻要努力学习，要不然你会后悔的。 
        He looked everywhere as if(he was) in search of something. 他到处看似乎在找什么东西。 
注意：
①当从句的主语和主句的宾语一致时，间或也有这样的省略。
如：Her father told her to be careful when(she was) crossing the street. 当她过马路时父亲告诉她要当心。
②当从句的主语是it，谓语动词中又含有系动词be时，可以把it和系动词be一起省略。此时构成连词（if, unless, when, whenever）+形容词的结构。
如：Unless(it is) necessary, you'd better not refer to the dictionary. 如果没有必要，你最好不要查字典。

2、定语从句中的省略：
1）一般说来，在限制性定语从句中，作宾语的关系代词that,which,whom可以省略；
如：Is this reason(that) he explained at the meeting for his carelessness in his work?
这就是他在会上解释他工作中粗心的原因吗？
而在非限制性定语从句中作宾语的关系代词which, whom不可以省略。
比较：Tom(whom) you saw yesterday fell ill.(whom可以省)   你昨天见到的汤姆病倒了。
            Tom, whom you saw yesterday, fell ill. (whom不可以省) 汤姆病倒了，你昨天见到他了。
2）在口语和非正式用语中，关系副词when, where,和why经常用that来代替，甚至还可省略。
如：This is the first time(when/that) he had trouble with the boss.
这是他第一次麻烦老板。
        He wants to find a good place(where/that) we can have a picnic during the"golden week"holiday.
他想找一个能在黄金周期间野餐的好地方。
        Could you tell us the reason(why/that) he was so unhappy?
你能告诉我们他为什么如此不高兴吗？
3）当先行词为表示方式的the way时，从句不能用how来引导，应该用that或in which，或将它们全部省略。
如：I don't like the way(that/in which) you laugh at her.
我不喜欢你嘲笑他的行为。

3、宾语从句中的省略：
1）在及物动词后面所接的宾语从句中，连词that一般可以省略；但如果及物动词后面是由that引导的两个或两个以上的并列的宾语从句，那么只有第一个that可以省略。
如：I think(that) the reform of the renminbi's exchangerate is necessary. 我认为人民币兑换率的改革是必要的。
       He said(that) the Anti-secession law had been passed and that President Hu Jintao had signed a presidential order.
他说《反分裂国家法》已被通过，而且胡锦涛主席已签署了主席令。
2）由which, when, where, how, 和why引导的宾语从句，可以全部或部分省略。
如：I know that NBA star YaoMing will come to our city but I don't know when (he will come to our city).
我知道NBA明星要到我们城市来但我不知道他什么时候来。
       He wants to move abroad but his parents wonders why(he wants to move abroad)
他想搬迁到国外但他的父母想知道为什么。

4、在与suggest, request, order, advise等词相关的名词性从句中，须用虚拟语气形式“should+动词原形”，should可以省略：
如：Chirac, President of the Republic of France suggested that the China-France Culture Year(should) last long in various forms.
法国总统希拉克建议中法文化年以各种各样的形式长期持续。

5、主句省略多用于句首：
如：(It is a) Pity that I didn't go to Mary's birthday party yesterday.
很遗憾，我昨天没有去参加玛丽的生日聚会。

6、在答语中，主句可全部省略。
如：—Why were you absent from school last Friday?
        —(I was absent from school) Because my mother was ill.
        —上周五你为什么没有上学？
        —因为我妈妈病了。

动词不定式省略：

1、保留to的场合：
（1）不定式作某些动词的宾语时，这些动词常见的有：
love, like, care, wish, hope, expect, prefer, refuse, mean, try, oblige, advise, persuade, agree, want, afford, forget, remember, try, manage等。
如：—You should have thanked her before you left.
        —I meant to, but when I was leaving I couldn't find her anywhere.   
        —你本该在离开前谢谢她。
        —我本打算这么做，但当我就要离开的时候我却找不到她了。
       You can do it this way if you like to. 如果你想做，你可以这么做。
（2）不定式作某些动词的宾语补足语或主语补足语时，这些动词常见的有：
ask, tell, advise, force, persuade, wish, allow, permit, forbid, expect, order, warn 等。
如：The boy wanted to ride his bicycle in the street, but his mother told him not to. 男孩想在街上骑他的自行车，但他母亲不让。
        She wants to come but her parents won't allow her to(come).　她想来，可是她父母不让。
（3）不定式在句中作某些形容词的状语时，常见的形容词有：
happy, glad, eager, anxious, willing, ready 等。
如：—I will be away on a business trip. Could you mind looking after my cat?　
        —Not at all. I would be happy to (look after your cat).　
        —我要出差，你能帮我照顾一下我的猫吗？
        —没关系，我很愿意。
（4）不定式作某些复合谓语时，常见结构如：be able to, be going to, have to, ought to, used to 等。
如：He doesn't like fish but he used to. 他现在不喜欢吃鱼，但过去喜欢。

2、省略to的场合：
（1）主语部分有to do，系动词is或was时，作表语的不定式通常省去to。
          如：The only thing you have to do is press the button. 你必须做的惟一事情是按按钮。
（2）作介词but, expect, besides的宾语，前面又有实意动词do时，不定式通常省去to。
          如：He said that Chen Shuibian had nothing to do except push a pro-"independence"timetable.
                  他说陈水扁除了推进支持“独立”的时间表外，什么也没有做。
（3）主语部分暗含todo，表语中的不定式通常省去to。
          如：All I want(to do) is go to school and study hard. 我想要（做）的就是上学，努力学习。
（4）当两个或多个不定式并列时，其后的不定式符号可以省略，但有对比关系时不可省略。
          如：It is easier to say than to do. 说起来容易，做起来难。
（5）在would rather...than...等结构中，不定式符号常常要省略。
          如：I would rather stay at home than go to see a film. 我宁愿呆在家也不愿去看电影。
（6）在see, watch, notice, hear, listen to, look at, feel, have, make, let, observe等词后作宾语补足语时省略不定式符号to；why(not)do结构中，不定式不带to。
          如：I saw her enter the room. 我看见她进入了房间。　
                 Why not join us? 为什么不加入到我们的行列里来呢？

虚拟语气的概念：

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。

虚拟语气在条件句中的应用：

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.
典型例题：
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。
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。)
典型例题：
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）

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：

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。
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。
但要注意，在虚拟条件状语从句中，省略连词的倒装形式的句首不能用动词的缩略形式。如我们可说Were I not to do.，而不能说Weren't I to do。