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初中三年级英语

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  • 单选题
    "For your coming vacation, why _________ corning to Guiyang?" "Good idea!"
    A. not consider    B. don't consider   C. to consider

    本题信息:英语单选题难度一般 来源:未知
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本试题 “"For your coming vacation, why _________ corning to Guiyang?" "Good idea!"A. not consider B. don't consider C. to consider” 主要考查您对

祈使句

感叹句

反意疑问句

表语从句

等考点的理解。关于这些考点您可以点击下面的选项卡查看详细档案。
  • 祈使句
  • 感叹句
  • 反意疑问句
  • 表语从句
祈使句:
表示请求或命令的句子是祈使句。祈使句一般用降调,为使祈使句听起来比较婉转,可用低声调,祈使句句末用句号或感叹号。
每种类型又有肯定形式和 祈使句的组成
①动词原形+其他
②Please+动词原形+其他
③否定形式:don‘t+动词原形,用don’t否定时,只能用其缩略形式。
例如:
Welcome to Beijing Park. 
Walk about three blocks. 
Don’t mention it.

 

祈使句含义:

1. 表请求 
Pass me the sugar, please.
请把糖递给我。

2. 表命令 
Put up your hands.
举手。 
Fill in this form.
把这个表填好。

3. 表建议 
Let
s have dinner together. 我们共进晚餐吧。

4. 表邀请 
Come in and have a seat.
进来请坐。 
Help yourself to some fruits.
请吃水果。

5. 表警告 
Hurry up or you will be late.
抓紧点,不然你要迟到了。 
Do that again and you
ll be in trouble.要是再干那事,你会有麻烦的。

6. 表禁止 
Don
t touch the exhibits.不要触摸展品。 
Don
t play on the road.不要在马路上玩耍。

7. 表叮嘱             
Be sure to get there before nine.
务必在九点前赶到那里。 
Take care not to catch cold.
小心别着凉了。

8. 表号召 
Workers of all countries, unite!
全世界工人阶级联合起来!

9. 表祝愿 
Have a good trip.
祝你旅途愉快。


祈使句有三种类型:
一、含第二人称主语的祈使句
1. 当祈使的对象是第二人称you时称为含第二人称主语的祈使句。
这时,主语you通常不出现在句中,谓语动词用原形。
有时在句首或句末加please,还可加上称呼语,用逗号与句子主体隔开。如:
Please be quiet, boys! 孩子们,请安静!
Come this way, please. 请走这边。
如要加强语气,可在动词前加do。如:
Do keep away from the fire! 切记远离火种!
2. 否定式在谓语动词前加Don’t或Do not,强调否定式则在动词前加Never。如:
Don’t alway make the same mistake. 不要老犯同一个错误。
Never be late again. 千万别再迟到了。
3. 有时,为了强调指明向谁提出要求或发出命令,或表达说话人的急躁、厌烦、不满、恼怒的情绪,就用主语you表示,且放在动词前。如:
You come here! 你到这里来!
You mind your head! 小心别碰到头了!
若为否定式,则把Don’t放在主语you之前。如:
Don’t you come here! 你别来这里!

二、含第一、第三人称主语的祈使句
1. 含第一或第三人称主语的祈使句通常以Let开头,
第一人称由“Let + me / us +动词原形”构成,
第三人称由“Let + 第三人称代词(用宾格)或名词+动词原形”构成。
这类祈使句往往用于提出建议。如:
Let me have a try if you don’t want to. 如果你不想,就让我试一试吧。
Let’s spend this weekend in the country. 咱们到乡下去度这个周末吧。
Let him be here by ten o’clock. 叫他10点到这里吧。
有时也可以先称呼对方的名字,,后跟一句无人称主语的祈使句。如:
Jane, sit down please. 简,请坐下。
Mum, remember to bring me an umbrella. 妈妈,记得给我带把伞。
2. 这类祈使句的否定式是在动词原形前加not,也可以在let前加Don’t。如:
Let’s not wast our time about it. 我们不要为了这件事而浪费时间。
Don’t let us wait here. 别让我们在这儿等。
Don’t let him go out. 别让他出去。

三、无动词祈使句
在请求、命令和口号中,常用无动词祈使句,它实际上是省略了动词,从而使语句更简洁或有力。如:
Just a minute, please! 请稍等!
This way, please! 请这边走!
Attention! 立正!
Up the stairs! 上楼!
To the playground, everyone of you! 到操场上去,你们每个人都得去!
在一些指示牌上,常用“No +动名词/名词”构成简略式的否定祈使句。如:
No smoking! 禁止抽烟!
No parking! 禁止停车!
No photos! 禁止拍照!
还有一些是祝词类的无动词祈使句,如:
May you succeed!祝你成功!
Long live our friendship!我们的友谊万岁!



祈使句特点口令:
祈使句无主语, 主语you常省去;
动词原形谓语当, 句首加don't否定变;
朗读应当用降调, 句末常标感叹号。

祈使句的语调特点 :
1、语音强度一般比陈述句重,书面上用叹号表示。
2、句末用降调,较长句子的后半部分几个音节速度加快。

对特定的人使用的祈使句:
祈使句如Wait here! (在这儿等着!) 可以是对一个人说,也可以是对几个人说,其主语暗含you。
但我们却可以用下列方式引起我们说话的对象的注意:
■You+祈使语气动词
You wait here for a moment. 你在这儿等一会儿。
语调和重音很重要。在上面这一句里,如果不重读you,那么句子的意思是this is where you wait (这就是你应等着的地方);
如果重读you,那么句子的意思就是this is what I want you to do (这是我要你做的事)。
此外,重读you时还可以表示愤怒、敌意或不客气。如:
You mind your own business! 不关你什么事
You try teaching 40 noisy children five days a week! 你来试试每周5天教40个吵闹的孩子!
在否定句中Don’t要重读 (不重读you)。如:
Don’t you speak to me like that! 你别这样跟我讲话!

■“you+人名”或“人名+you”
You wait here, Jim, and Mary, you wait there. 你等在这儿,吉姆;玛丽,你等在那儿。

■“祈使语气+人名”或“人名+祈使语气”:
Drink up your milk, Sally! 把你的牛奶喝光,萨利!
Sally, drink up your milk! 萨利,把你的牛奶喝光!

■祈使语气+反身代词
Enjoy yourself. 你好好享受吧。
Behave yourself. 你放规矩点。

■对一群人讲话时,祈使语气可与everybody, someone之类的词连用:
Everyone keep quiet! 大家安静!
Keep still everybody! 每个人都保持不动!
Nobody say a word! 都不许说话!
Somebody answer the phone please. 请来个人接电话。

■在表示否定的命令语气后面可用带any的复合词
Don’t say a word anybody! 谁都不要说话!
Don’t anybody say a word! 任何人都不许说话!


感叹句:
是表示喜怒哀乐等情感的句子。感叹句一般用how或what开头。感叹句要用降调,句末用感叹号
How作状语,修饰修饰形容词、副词、或句子;
what作定语,修饰名词(名词前可有形容词或冠词)。
感叹句结构:
一、由感叹词what引导的感叹句。
1.① What+a/an+(形容词)+单数可数名词+主语+谓语!
② What+名词词组+主语+谓语!
如: What a fine day it is!
2. What+(形容词)+可数名词复数或不可数名词+主语+谓语!
如: What kind women they are!
What nice music it is!

二、由How引导的感叹句。(how用来修饰形容词、副词或动词。)
1.How+形容词(副词)+主语+谓语!
如: How hard the workers are working!
How clever the girl is!
How quickly the boy is writing!
2. How+主语+谓语!
如:How time flies! 时光飞逝!

三、注意:
1. 当how修饰动词时,动词不跟着感叹词提到主语之前。
如: How fast the runner runs!
2. how与what引导的感叹句中的第一种格式(单数名词)一般情况下可以相互转换,转换后意义不变。
如: What an interesting story it is! = How interesting the story is!
What a beautiful building it is! = How beautiful the building is!
3. 在口语中,感叹句的主语和谓语常常省略。
如: What a nice present!(省略it is)
How disappointed!(省略she is或其它可作本句主、谓的词语)
感叹句 what 和 how 的区别:
1.由"what"引导的感叹句:"what"意为"多么"用作定语,修饰名词(被强调部分),单数可数名词前要加不定冠词a/an,复数可数名词或不可数名词前不用冠词。
这类句子的结构形式是:
what+(a/an)+adj.+n.+主语+谓语+(it is).
如: What a clever girl she is!   多么聪明的姑娘呀!
 
2.由"how"引导的感叹句:"how"意为"多么",用作状语,修饰形容词或副词(被强调部分)。
如果修饰形容词,则句中的谓语动词用系动词;
如果how修饰副词,则句中的谓语动词用行为动词,这类句子的结构形式是:
How+adj.(adv.)+主语+谓语+(it is).
如: How cold it is today!今天多么冷呀!
  
3.在表示同一意义时,英语感叹既可用"what"引导,也可用"how"引导。如:
What a hot day it is!
How hot the day is !

4.感叹句在表示激动强烈的感情时,口语中常常采用省略句,其后面的主语和谓语往往略去不讲。
如:What a fine day! 多么晴朗的天呀!

一般陈述句转换成How或者What引导的感叹句的方法:
方法:
找出陈述句中的主语和谓语部分,再找出形容词,最后找陈述句中是否包含该形容词修饰的名词部分。
例如:My classmates are very kind and helpful.
分析:
句子的主语是my classmates,谓语(即动词)是are,形容词有kind和helpful,但没有该形容词要修饰的名词。
因此可以转换成How引导的感叹句,根据“How + adj. + 主语 + 谓语!”,
该陈述句可以改成:
How kind and helpful my classmates are!

例如:China is a peaceful country.
分析:
句子中的主语是China,谓语是is,形容词是peaceful,而且有该形容词修饰的名词country,并且,country是可数名词,需要用冠词,原句有冠词a,
因此可以转换成What引导的感叹句,根据“What + n. + 主语 + 谓语!”,
该句子可以改成:
What a peaceful country China is!

感叹句用法:
感叹句多以how或what引导,但在口语中,还有一些特殊的感叹句表达形式。
1.以副词here, there, in开头的感叹句。
Here comes the bus! 公共汽车来了!
There they are! 他们在那儿呢!
2.以疑问词who开头,表示惊奇。
Who else will read such a book! 谁还会读这样的书!
3.以情态动词may开头,表示愿望。
May you both be happy! 祝二位幸福。
May you succeed! 祝你成功!
4.否定疑问句用作感叹句时,它的意义是肯定的;但肯定疑问句用作感叹句在美国英语中比较常见。
Aren’t they sweet! 他们多可爱啊!
I am hungry! 我饿极了!
5.一些短语用作感叹句。
Dear me! 哎呀! My goodness! 嗳呀!
None of your nonsense! 不要胡说了!
6.一些作表语的成分用作感叹句。
Just my luck! 又倒霉了!
Sorry, my mistake! 对不起,是我的错!
7.以从句表示的感叹句。例如:
As if were my fault!好像是我的错似的!
To think a scandal of this sort should be going on under my roof!真想不到这种丑事竟然出在我们家里!


感叹句大全:
一、由 what 引导的感叹句,其句子结构可分为以下三种:
“ What + a/an +形容词+可数名词单数+主语+谓语!”。如:
What a nice present it is! 它是一件多么好的礼物啊!
What an interesting book it is! 它是一本多么有趣的书啊!
“ What +形容词+可数名词复数+主语+谓语!”。如:
What beautiful flowers they are! 多么漂亮的花啊!
What good children they are! 他们是多么好的孩子啊!
“ What +形容词+不可数名词+主语+谓语!”。如:
What fine weather it is today! 今天天气多好啊!
What important news it is! 多重要的新闻啊!

二、由 how 引导的感叹句,其句子结构也分为三种:
“ How +形容词 / 副词+主语+谓语!”。如:
How careful she is! 她多么细心啊!
How fast he runs! 他跑得多快啊!
“ How +形容词+ a/an +可数名词单数+主语+谓语!”。如:
How beautiful a girl she is! 她是个多么漂亮的姑娘啊!
“ How +主语+谓语!”。如:
How time flies! 光阴似箭!
由 what 引导的感叹句与由 how 引导的感叹句有时可以转换,但句中部分单词的顺序要有所变化。如:
How beautiful a girl she is! = What a beautiful girl she is!
What delicious cakes these are! = How delicious these cakes are!

三、有时感叹句也可以由一个单词、词组、祈使句、陈述句等构成。
如: Good idea! (好主意!)
wonderful! (太精彩了!)
Thank goodness! (谢天谢地!)
反义疑问句:
表示提问人的看法,没有把握,需要对方证实。
反意疑问句由两部分组成:前一部分是一个陈述句,后一部分是一个简短的疑问句,两部分的人称时态应保持一致。
1. 陈述部分肯定式+疑问部分否定式可记为前肯后否。 
2. 陈述部分否定式+疑问部分肯定式可记为前否后肯。
例如:This pencil is red, isn’t it? Yes, it is. / No, it isn’t. 
               This pencil isn’t red, is it? Yes, it is. / No, it isn’t.
速记:
前肯后否,前否后肯,前be后be,前无be后加助,时态一致。

反意疑问句的回答
前肯后否,前否后肯,根据事实从后往前翻译。如:
(1)They work hard,don’t they?他们努力工作,不是吗?
Yes, they do.对,他们工作努力。/No, they don't.不,他们工作不努力
(2)They don’t work hard, do they? 他们不太努力工作,是吗?
Yes, they do. 不,他们工作努力。/No, they don't. 是的, 他们工作不努力

否定反义疑问句的回答
当陈述部分为肯定式,反义疑问句为否定式时,其回答一般不会造成困难,一般只需照情况回答即可:
"It’s new, isn’t it?" "Yes, it is." “是新的,不是吗?”“是,是新的。”
"He wants to go, doesn’t he?" "No, he doesn’t." “他想去,不是吗?”“不,他不想去。”
此时,"Yes"即是,对前面"It's new."的肯定。

回答反义疑问句的原则
回答反意疑问句通常应根据实际情况来确定,
如有人问你You are asleep, aren’t you? 你应回答No, I’m not. 因为既然你能回答,肯定你还没有asleep。
但如果别人问你 You aren’t asleep, are you?(你还没有睡着,对吗),你也只能回答No, I’m not.(是的,还没有睡着),而不能回答为Yes, I’m not. 也不能回答成 Yes, I am.
“It is a beautiful flower,isn't it?” “It isn't a beautiful flower,is it?”
上述两句句子的回答肯定均为“Yes,it is."否定为“No,it isn't."
由上述例子可知,反义疑问句回答与句子本身所包含的中文肯定与否的含义并无太大关联,只需注意事实,肯定即用yes,否定用no,无需考虑句子原本是前否后肯或是前肯后否。

口诀:
反意疑问并不难,陈述疑问句中含。
前后肯否恰相反,否定词缀不能算。
主谓时态要一致,特殊情况记心田。
实际情况来回答,再把yes和no拣。
综上所述,反义疑问句回答就是按实际情况回答。
对反意疑问句的回答,无论问题的提法如何,如果事实是肯定的,就用yes,事实是否定的,就要用no。
要特别注意陈述句部分是否定结构,反意疑问句部分用肯定式提问时,回答yes或no与汉语正好相反。这种省略回答的yes要译成“不”,no要译成“是”。
例:
—He likes playing football, doesn’t he? 他喜欢踢足球,不是吗?
—Yes, he does. / No, he doesn’t. 是的。/ 不是。
—His sister didn’t attend the meeting, did she? 他妹妹没有参加会议,是吗?
—Yes, she did. / No, she didn’t. 不,她参加了。/ 是的,她没参加。


快速记忆表:
陈述部分的谓语   疑问部分
I/主语   aren't I / are I
no,nothing,nobody,never,few, seldom, hardly,rarely, little等否定含义的词   肯定含义
含有un-,in-.dis-,im-等否定意义的前缀构成的词语时,视为肯定含义   否定含义
ought to(肯定的)   shouldn't/ oughtn't +主语
have to+v.(had to+v.)   don't +主语(didn't +主语)
used to+v.   didn't +主语或 usedn't +主语
had better + v.   hadn't you
would rather + v.   wouldn't +主语
you'd like to + v.   wouldn't +主语
must   根据实际情况而定
感叹句   be +主语
指示代词或不定代词everything,that,nothing,this   主语用it
并列复合句   谓语根据邻近从句的谓语而定
定语从句,宾语从句主从复合句   根据主句的谓语而定
think,believe,expect,suppose,imagine等引导   与宾语从句相对应的从句
everybody,anyone,somebody,nobody,no one   复数they, 单数he
情态动词dare或need   need/needn't (dare/daren't ) +主语
dare, need 为实义动词   do/don't +主语
省去主语的祈使句   will/won't you?
Let's 开头的祈使句   Shall we?
Let us 开头的祈使句   Will you?
there be   相应的谓语动词+there(省略主语代词)
否定前缀不能视为否定词   仍用否定形式.
反意疑问句19条:
1) 陈述部分的主语是I,疑问部分要用 aren't I.
I'm as tall as your sister,aren't I?
2) 陈述部分的谓语是wish,疑问部分要用may +主语。
I wish to have a word with you, may I?
3) 陈述部分用 no, nothing, nobody, never, few, seldom, hardly, rarely, little等否定含义的词时,疑问部分用肯定含义。
The Swede made no answer, did he / she?
Some plants never blown (开花), do they ?
4) 含有ought to 的反意疑问句,陈述部分是肯定的,疑问部分用shouldn't / oughtn't +主语。
He ought to know what to do, oughtn't he? / shouldn't he?
5) 陈述部分有have to +v. (had to + v.),疑问部分常用don't +主语(didn't +主语)。
We have to get there at eight tomorrow, don't we?
6) 陈述部分的谓语是used to 时,疑问部分用didn't +主语或 usedn't +主语。
He used to take pictures there, didn't he? / usedn't he?
7) 陈述部分有had better + v. 疑问句部分用hadn't you?
You'd better read it by yourself, hadn't you?
8) 陈述部分有would rather +v.,疑问部分多用 wouldn't +主语。
He would rather read it ten times than recite it, wouldn't he?
9) 陈述部分有You'd like to +v. 疑问部分用wouldn't +主语。
You'd like to go with me, wouldn't you?
10) 陈述部分有must 的疑问句,疑问部分根据实际情况而定。
He must be a doctor, isn't he?
You must have studied English for three years, haven't you? / didn't you?
He must have finished it yesterday, didn't he?
11) 感叹句中,疑问部分用用否定的助动词加sb/sth?如:
1)What a fine day it is today!
What a fine day it is today,isn“t it?
2)How fast he runs!
How fast he runs,doesn”t he?
3)What a long time we have been waiting!
What a long time we have been waiting ,haven“t we?
12) 陈述部分由neither… nor, either… or 连接的并列主语时,疑问部分根据其实际逻辑意义而定。
Neither you nor I am engineer, are we?
13) 陈述部分主语是指示代词或不定代词everything, that, nothing, this, 疑问部分主语用it。
Everything is ready, isn't it?
14)陈述部分为主语从句或并列复合句,疑问部分有三种情况:
a. 并列复合句疑问部分,谓语动词根据邻近从句的谓语而定。
Mr. Smith had been to Beijing for several times, he should have been in China now, shouldn't he?
b. 带有定语从句,宾语从句的主从复合句,疑问部分谓语根据主句的谓语而定:
He is not the man who gave us a talk, is he?
He said he wanted to visit Japan, didn't he?
c. 上述部分主句谓语是think, believe, expect, suppose, imagine等引导的定语从句,疑问部分与宾语从句相对应构成反意疑问句。
I don't think he is bright, is he?
We believe she can do it better, can't she?
15) 陈述部分主语是不定代词everybody, anyone, somebody, nobody, no one等,疑问部分常用复数they,有时也用单数he。
Everyone knows the answer, don't they? (does he?)
Nobody knows about it, do they? (does he?)
16) 带情态动词dare或need的反意疑问句,疑问部分常用 need (dare ) +主语。
We need not do it again, need we ?
He dare not say so, dare you?
当dare, need 为实义动词时,疑问部分用助动词do + 主语。
She doesn't dare to go home alone, does she?
17) 省去主语的祈使句的反意疑问句,疑问部分用will you。
Don't do that again, will you?
Go with me, will you / won't you ?
注意: Let's 开头的祈使句,后用shall we?
Let us 开头的祈使句,后用will you?
Let's go and listen to the music, shall we?
Let us wait for you in the reading-room, will you ?
18) 陈述部分是"there be"结构的,疑问部分用there省略主语代词。
There is something wrong with your watch, isn't there?
There will not be any trouble, will there?
19) 否定前缀不能视为否定词,其反意疑问句仍用否定形式。
It is impossible, isn't it?
He is not unkind to his classmates, is he?
有些动词如:cost hurt hit put 等,它们的过去时与原型相同,在肯定句中一定要先弄清楚它们是什么时态.
英语18种特殊的反意疑问句:
1.祈使句。祈使句后一般加上will you或won't you构成反意疑问句,用will you 多表
示“请求”,用won't you 多表示提醒对方注意。例如:    
Look at the blackboard, will you/ won't you?看黑板,好吗?   
Let 引导的祈使句有两种情况:   
1) Let's...后的反意疑问句用shall we或shan't we。例如:   
Let's go home, shall we/ shan't we? 回家吧,好吗?    
还可以用may I来表示征求对方的同意或许可。   
2) Let us/me...后的反意疑问句用will you或won't you。例如:    
Let me have a try, will you/won't you? 让我试一试,行吗?   
2. 感叹句。感叹句后加反意疑问句时,其反意疑问句需用be的一般现在时态的否定形式。 例如:   
What fine weather, isn't it? 多好的天气啊,是吧?    
3. 当陈述部分谓语动词是need, dare, used to,且这些词被用作实义动词时,其反意疑问 句需用do的适当形式。例如:   
He needs help, doesn't he? 他需要帮助,是吗?    
4. 陈述部分主、谓语是I am...时,反意疑问句用aren't I 或am't I ,而不是am not I (可 用a m I not)。例如:   
I'm working now, am't I? 我在工作,是吗?   
5. 陈述部分的主语是everything, nothing, anything或something 时,反意疑问句的主语应用代词it。例如:    
Something is wrong with my radio, isn't it? 我的收音机出毛病了,是吧?   
6. 陈述部分的主语是 everybody, everyone, anybody, anyone, somebody, someone, nobody, no one, none, neither 时, 其反意疑问句的主语需用复数代词they。 例如:   
Everyone is here, aren't they? 大家都到了,是吗?   
No one knows about it, do they? 没有人知道这件事,对吗?   
7. 陈述部分的主语是指示代词this或that时,反意疑问句的主语用it,当陈述部分的主语是指示代词these或those时,其反意疑问句的主语用they。 例如:   
This is a plane, isn't it? 这是一架飞机,是吗?   
These are grapes,aren't they? 这些是葡萄,是吗?   
8. 陈述部分的主语是不定代词one时,反意疑问句的主语可以用one,也可用you(美式英语用he)。例如:   
One should be ready to help others, shouldn't one? 每个人都应该乐于助人,是吧?   
9. 当陈述部分含有以下这些含有否定意义的词时:few, little, seldom,hardly, never, not,  no, no one, nobody, nothing, none, neither等,其反意疑问句需用肯定结构。 例如:    
He is never late for school, is he? 他上学从不迟到,是吗?   
10. 当陈述部分所含的否定词是通过加前缀或后缀构成的,其后的反意疑问句依然用否定结构。例如:   
   It is unfair, isn't it? 这不公平,是吧?   
11.含有否定含义的词在陈述部分作动词的宾语时,其反意疑问句用肯定结构,也可以用否定结构。例如:   
You got nothing from him, did you? 你从他那儿什么也没得到,是吗?   
12. 当陈述部分主语是从句、不定式(短语)、动词-ing形式时,反意疑问句的主语应该用it。  例如:   
What you need is more important, isn't it?你需要的东西更重要,是吧?   
13. 当陈述部分含I think (believe, suppose...)that... 结构时,其反意疑问句须与从句的主、谓语保持一致,注意主句的主语必须是第一人称。例如:   
I don't think he will come, will he? 我认为他不会来,对吗?   
14.have(has)不是表示“有”的意思,并在句中做谓语时,其反意疑问句的助动词要用do, does, did。例如:   
They had a meeting just now,didn't they? 他们刚才开了个会,是吗?   
15. 陈述部分有have to 时,其反意疑问句要用助动词的否定形式。例如:   
You have to water the vegetables every day, don't you?你每天都要浇菜,对吧?   
16. 陈述部分是there be句型时,其反意疑问句中要用there。例如:   
There was a hospital here, wasn't there? 过去这儿有家医院,是吗?   
17. 陈述部分有had better时,反意疑问句中要用hadn't。 例如:   
We had better go to school at once, hadn't we? 我们现在最好马上去上学,好吗?
18. 当陈述部分含有情态动词must时,我们便要分析一下must的含义。如果must 作“一定;要;必须”讲,反意疑问句须用mustn't或needn't;
而当must作推测意义“一定 是;必定”讲时,反意疑问句则需根据must后的动词原形选用相应的形式。例如:    
He must work hard at physics, mustn't he? 他必须努力学物理,是吧?   
Tom must be at home,isn't he? 汤姆一定在家,是吧?
表语从句:
就是用一个句子作为表语。说明主语是什么或者怎么样,由名词、形容词或相当于名词或形容词的词或短语充当,和连系动词一起构成谓语。
表语从句是名词性从句的一种。
表语从句的基本结构是:
“主语+连系动词+关联词+表语从句”。
连接表语从句的连接词有:
that, what, who, when, where, which, why, whether, how, whoever,whomever,whichever ,whatever等。
例如:The question is when he can arrive at the hotel. 
            His suggestion is that we should stay calm.
①语序:
从句的语序必须是陈述句语序,即“主语+谓语”这种形式。
②时态:
当主句是一般现在时或一般将来时的时候,从句可以是任何时态,而当主句是一般过去时的时候,从句,从句时态必须是过去时范围的时态,即(一般过去时,过去进行时,过去完成时,过去将来时)。
③连接词:
当从句意思完整,主句意思肯定时,连接词用that,且可以省去,当从句意思完整,主句意思不确定或含否定含意时,常用if或whether(是否),当从句意思不完整时,连接词则是代替不完整部分的特殊疑问词。
表语从句种类:
根据关联词来区分,表语从句可以分为六种:
一、由that引导的表语从句
The trouble is that he misunderstood me.麻烦的是他误解了我。
有时,引导表语从句的连词that可以省略
The truth is (that) I didn’t finish my term essay. 事实是我没有写完学期论文。

二、由连接代(副)词引导的表语从句
连接代词who, whom, whose, what, which, whoever, whatever, whichever;
连接副词where, when, how, why。
That was what she said this morning in her bedroom.那就是她今天早晨在卧室中说的。

三、由关系代词型的what引导的从句
I want to be a teacher. That’s what I want to be.
我想当老师,那是我的志愿。

四、关联词是连词because
比较下面这两个句子:
I was angry. That was because he didn’t understand me.
我生气是因为他不理解我。(表语从句强调原因)
That’s why he got fired from that firm.那正是他被公司解雇的原因。(表语从句强调结果)
注意:reason作主语或主语中包含事件的起因时,后面的表语从句表示原因时要用that来引导,而不用because
That is why ...是常用句型,其中why引导的从句在句中作表语,该句型通常用于针对前面已经说过的原因进行总结。
1. That is the reason why ...That is the reason why ...与That is why ...是同义的,
但是从语法结构上讲,That is the reason why ...中的why引导的是一个定语从句,将其中的the reason去掉后则与That is why ...结构一样了
2. That is because ...That is because ...也是一个常用句型。
That is because ...句型中,连词because引导的从句作表语,
That is because ...与That is why ...之间的不同在于That is because ...指原因或理由,
That is why ...则指由于各种原因造成的结果
He did not read Harry Potter last night. That is because he had to help his mother to do the housework.
昨天晚上他没有读《哈里波特》,那是因为他得帮助他妈妈做家务。

五、关联词是从属连词whether, as, as if
The question remains whether we can win the majority of the people.
问题是我们能否赢得大多数民众的支持。

六. 使用虚拟语气的表语从句
在表示建议、劝告、命令含义的名词后的表语从句,谓语动词需用“should+动词原形” 表示,should可省略。
常见的词有:advice,suggestion,order,proposal,plan,idea等。
My suggestion is that we (should) start early tomorrow.
我的建议是我们明天一早就出发。

表语从句中需要注意的地方:
1. 表语从句一定要用陈述语序;
2. 不可以用if,而用whether 连接表语从句(as if 例外);
3. 与宾语从句不同,在有表语从句的复合句中,主句时态和从句时态可以不一致。
4. 连接词that一般不能省略,但当主句中含动词do的某种形式时,that可以省略。如:
What I want to do is (that) I can go up to him and thank him. 我想做的事是走到身边去感谢他。
5. 当句子的主语是:advice, demand, decision, desire, idea, insistence, instruction, order, plan, proposal, recommendation, request, requirement, suggestion, wish等名词时,
表语从句须用虚拟语气,即:should +do。如:
My advice is that you should go to apologize to him. 我的建议是你应该去向他道歉。


表语从句语法提示:
应注意的问题:
1. 连系动词be,appear,seem,look等之后可以跟表语从句。
It was because he didn't pass the exam.那是因为他没有通过考试。

2. 引导表语从句的引导词有以下几类。
1)wh-疑问词
My question is who left.我想问的是谁离开了。
2)whether
My question is whether he left(or not)。 我的问题是他是否离开了。
注:if不能引导表语从句。
3)that
The fact is that he left. 事实是他离开了。
注:引导表语从句的连词that间或可以省略。
The truth is(that)I didn't go there. 事实是我没去那儿。
4)because,as,as if,as though
It's just because he doesn't know her. 这是仅仅因为他不认识她。

3.表语从句要用陈述语序
That is where the famous scientist was born.

4.that和what在引导表语从句时,作用和意义都不相同。
That本身没有词义,在句中只起连接作用,不充当句子成分;what则表示“所……的(人或事)”,在表语从句中充当主语或宾语等。
That fact is that more than seventy percent of the earth’s surface is covered by water.

5.If 与whether均意为“是否”,但引导表语从句时,只能用whether, 不能用if。
The question is whether we can finish our work by tomorrow evening.

6.As, if, though引导的表语从句时,从句谓语多用虚拟语气。
这是因为从句中的情况与事实不相符。具体来说,如果从句表示与现在事实相反,谓语动词用一般过去式;
如果从句表示与过去事实相反时,谓语动词要用“had +过去分词”,如果从句表示将来的可能性不大,用would (might ,could )+动词原形,如:
Li Lei is now in a new jacket he looks as if he were an American boy.
但是,如果as if ,as though 引导的表语从句所表示的与事实相符,从句则用陈述语气,如:
The clouds are gathering. It looks as if is going to rain.