一．虚拟语气
虚拟语气表示说话人的主观愿望、猜疑、建议或与事实不符的假设等，而不表示客观存在的事实。虚拟语气是由句中的谓语动词的特殊形式表示出来的。
虚拟语气主要分为与现在事实相反，与过去事实相反以及与将来事实相反三个种类。让我们一一来看下它们的结构和用法吧！
1、表示与现在事实相反的情况
从句：If+主语+动词一般过去时(Be动词用were)
主句：主语+ should/would/might/could+do：
If I were you，I would take an umbrella.
如果我是你，我会带把伞。（事实：我不可能是你）
If I knew his telephone number，I would tell you.
如果我知道他的电话号码，我就会告诉你。（事实：不知道）
If there were no air or water，there would be no living things on the earth.
如果没有水和空气，地球上就不会有生物。(事实：地球上既有空气也有水)
If I had any money with me，I could lend you some.
如果我带钱了，我就会借给你些。（事实：没有带钱）
If he studied harder，he might pass the exam.
如果他再努力些，就能通过考试了。（事实：没有努力）
If I were you， I'd wear a shirt and tie.
如果我是你，我就会穿衬衫和领带。(事实：我并不是你）
2、表示与过去事实相反的情况
从句：If+主语+had+done
主句：主语+should/would/might/could+have done
eg：If I had got there earlier，I should/would have met her.
如果我早到那儿，我就会见到她。（事实：去晚了）
If he had taken my advice，he would not have made such a mistake.
如果他听我的劝告的话，就不会犯这样的错误了。
（事实：没有听我的话）
3、表示与将来事实相反
从句：①if+主语+were to do
②if+主语+should+do
③if+主语+动词一般过去式（be动词用were）
主句：主语+should/would/might/could+do
eg：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，不可能）
If there were a heavy snow next Sunday，we would go skating.
如果下周日下大雪，我们就去滑冰。（事实：下雪可能性很小，不可能）
If she were to be here next Monday，I would tell her about the matter.
如果她下周一来这儿的话，我就会告诉她这件事的始末。（事实：来的可能性很小，不可能）
除了以上三种主要情况，虚拟语气还有以下几种结构和用法哦。
1、 当从句的谓语动词含有were，should，had时，if可以省略，这时从句要用倒装语序，即把were，should，had等词置于句首，这种多用于书面语。
eg：Should he agree to go there，we would send him there.
要是他答应去的话，我们就派他去了。
Were she here，she would agree with us.
如果她在这儿的话，她会同意我们的。
Had he learnt about computers，we would have hired him to work here.
如果他懂一些电脑知识的话，我们已经聘用他来这里工作了。
2、非真实条件句中的条件从句有时不表达出来，只暗含在副词、介词短语、上下文或其他方式表示出来，这种句子叫做含蓄条件句，在多数情况下，条件会暗含在短语中，如without…，but for…（要不是因为...）等
eg：
But for his help，we would be working now.
要不是他的帮助，我们还会在工作呢。
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。
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。
3、 有时，虚拟条件语气的从句中，主、从句可以省略其中的一个，来表示说话人的一种强烈的感情。
①省略从句
He would have finished it.
他本该完成了。
You could have passed this exam.
你本能通过这次考试的。
②省略主句
If I were at home now.
要是我现在在家里该多好啊。
If only I had got it.
我要是得到它了该多好啊。
4.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。
If I were you，I would go to look for him.
如果我是你，就会去找他。
二．倒装句
在英语中，主语和谓语是句子的核心，它们之间有两种语序：一是主语在谓语之前称为自然语序（Natural
Order）；二是主语在谓语之后则称为倒装语序（Inverted Order）。而倒装语序中又有完全倒装（Full
Inversion）和部分倒装（Partial Inversion）
1.完全倒装（Full Inversion）：又称"全部倒装",是指将句子中的谓语全部置于主语之前。此结构通常只用于一般现在时和一般过去时。
①谓语+主语+……
There be（的各种形式）+主语（+地点或时间状语）
例子：
There was a drop in the temperature.
温度下降了。
There are birds singing in the tree.
鸟儿在树上唱歌。
②副词+谓语动词+名词主语+……
例子：
Out rushed a young lady.
一个年轻的女士冲了出来。
③过去分词或现在分词+be动词的各种形式+主语+……
例子：
Scattered on the floor were several books and magazines.
几本书和杂志散落在地板上。
2.部分倒装（Partial Inversion）（又称半倒装句）：指将谓语的一部分如助动词或情态动词倒装至主语之前,而谓语动词无变化。如果句中的谓语没有助动词或情态动词，则需添加助动词do,does或did，并将其置于主语之前。
例如：
Nor did he let the disease stop him from living the kind of life he has always dreamt about.
疾病没有使他放弃过上梦想中的生活。
部分倒装也有以下几种常见类型：
1. 以否定词开头的句子要求部分倒装。注意下列句子中助动词或情态动词提前、甚至补充助动词的用法：
例：
Not until yesterday did little John change his mind.
小约翰直到昨天才改变了主意。
2.以否定副词开头并加状语放在句首的句子要求部分倒装。这些否定副词有barely, hardly, little, seldom,
scarcely…… when, never, no sooner…… than, rarely, no more, not nearly,
not only等以及only。
例：
Only in the country can you learn the “true English”.
只有处在本国，你才能学到“真正的英语。”
3.介词+no+名词的结构中需要用部分倒装，这些结构包括at no time; by no means; by no manner of
means; for no reason; in no case; in/under no circumstances; in no
sense; in no way; on no account; on no consideration; at no point
例：
Under no circumstances should you lend Paul any money.
无论如何，你都应该把钱借给保罗。
4. 由as引导的部分倒装句：
a) 当as作为比较意义时，即用于as + adj./ adv. + as结构中时，如果把第一个as省略掉，就形成部分倒装句。
例：
Cautious as the rest of her family (was) , she didn't seem willing to give an immediate reply to my question.
正如她家里人一样谨慎小心，她似乎不愿意立即回答我的问题。
She charged the stairs, quick as a rabbit (ran).
她跑上楼去，跑得象兔子那么快！
b) 当 as引导让步状语时，和although, though一样，当用作“尽管”之义时，可以用于部分倒装句。
Hard as he worked, he did not pass the exam.
虽然他很用功，但他还是没及格。
c) 表示原因时，为了强调起见，也可以倒装。
例：
Tired as he was, we decided not to disturb him.
因为他太累了，我们决定不打扰他。
d) 等于so时，意义是“也，也是”
例：
She worked hard, so/ as did her husband.
她工作很努力，她的丈夫工作也很努力。
三．独立主格
独立主格，首先它是一个“格”，而不是一个“句子”，在英语中任何一个句子都要有主谓结构，而在这个结构中，没有真正的主语和谓语动词，但又在逻辑上构成主谓或主表关系。
独立主格结构不是主谓完整的简单句，而只是一个短语。
其公式为：名词/名词短语/代词+不定式/ing分词/ed分词/形容词/副词/介词短语。名词前也可以加with。
独立主格结构主要用于描绘性文字中，其作用相当于一个状语从句，常用来表示时间、原因、条件、行为方式或伴随情况等。例如：
1) 表示时间
The meeting being over, all of us went home.
开完会后我们都回家了。
the meeting being over相当于when the meeting was over
Her work done, she sat down for a cup of tea.
她干完了活，坐下来喝茶。
her work done相当于when her work was done
2） 表示条件
The condition being favorable, he may succeed.
若条件有利，他或许能成功。
the condition being favorable相当于If the condition is favorable
3） 表示原因
There being no taxis, we had to walk.
没有出租车，我们只好步行。
There being no taxis相当于Since there was no taxis,
He wrapped her up with great care, the night being dark and frosty.
夜又黑又冷，所以他把她裹得严严实实的。
the night being dark and frosty相当于as the night was dark and frosty
4） 表示伴随情况
Almost all metals are good conductors, silver being the best of all.
几乎所有的金属都是良导体，而银则是最好的导体。
(=Almost all metals are good conductors, and silver is the best of all.)
5） 表示补充说明
We redoubled our efforts, each man working like two.
我们加倍努力，一个人干两个人的活。
独立主格有以下常见的七个类型：
类型1：名词（代词）+现在分词
We shall play the match tomorrow, weather permitting.
明天假设天气好，我们就进行比赛。
The monitor being ill, we’d better put the meeting off.
班长病了，我们最好还是延期开会吧。
类型2：名词（代词）+过去分词
The job finished, we went home.
工作结束后我们就回家了。
The last bus gone, we had to walk home.
最后一班公车已经走了，我们必须走路回家。
More time given, we should have done the job much better.
如果给我们更多的时间，我们会把工作做得更好。
类型3：名词（代词）+不定式
Nobody to come tomorrow, we will have to put off the meeting till next week.
如果明天没有人来，我们将把会议推迟到下周。
So many people to help him, he is sure to succeed.
有如此多的人来帮助他，他一定会成功的。
类型4：名词（代词）+介词短语
The soldiers dashed in, rifle in hand.
士兵们端着枪冲了进来。
A girl came in, book in hand.
一个少女进来了，手里拿着书。
He was waiting, his eyes on her back.
他在等着，眼睛望着她的背影。
类型5：名词（代词）+形容词或副词
He sat in the front row, his mouth half open.
他坐在前排，嘴半开着。
She sat at the table, collar off, head down, and pen in position, ready to begin the long letter.
她坐在桌前，衣领已解掉，头低了下来，拿好钢笔，准备开始写一封长信。
类型6：There being +名词（代词）
There being nothing else to do, we went home.
没有别的事可做，我们就回家了。
There being no further business, I declare the meeting closed.
没有再要讨论的事了，我宣布散会。
类型7：It being +名词（代词）
It being Christmas, the government offices were closed.
由于圣诞节的缘故，政府机关都休息。
It being a holiday, all the shops were shut.
由于今天是假日，所有商店都关门了。
