APP下载

必修3重点语法讲解

2020-11-02高雅丹

考试与评价·高一版 2020年3期
关键词:肯定句同位语否定句

高雅丹

一、情态动词

考点一、情态动词+have done

“情态动词+have done”的结构表示对过去的事情的推测、态度或看法。

1. must have done

must have done仅用于肯定句中,表示对过去所发生事情的推断,意为“一定已经”。

It must have rained last night, for the ground is wet. 昨晚一定下雨了,因为地面还是湿的。

2. can / could have done

can / could have done常用于疑问句和否定句中,表示对过去所发生事情的推测,意为“可能已经”;could have done用在肯定句中,表示“过去本来能够做某事而实际上没有做”。

There is no light in the room. Can they have gone out? 屋里沒有灯,他们可能出去了吗?

He could have passed the exam, but he was too careless. 本来他能够通过考试,但是他太粗心了。

3. may / might have done

may / might have done用于肯定句和否定句当中,表示对过去某一事情的推测,意为“可能已经”。

Philip may / might have been hurt seriously in the car accident. 菲利普可能在车祸中受了重伤。

4. should / ought to have done

should / ought to have done常用于肯定句和否定句中。用在肯定句中表示过去应该做而实际未做,其意为“本该……”;用在否定句中表示过去不该做而实际上已经做了,其意为“本不该……”。

Tom, you are too lazy. The work should have been finished yesterday. 汤姆,你太懒惰了,这项工作本来应该昨天就做完的。

5. need have done

need have done用于否定句或疑问句。用于否定句时,意为“本来不必”;用于疑问句时,意为“有必要……吗?”。

I needn't have bought so much wine—only five people came. 我本来没有必要买这么多酒,只来了五个人。

考点二、must, can, may表示对现在情况推测的比较

1. must

must表示猜测时常常用于肯定句,表示肯定猜测,语气较为强烈。

He must be in your room. 他肯定在你的房间里。

2. may

may表示猜测时常常用于肯定句和否定句,意为“也许”,语气较弱。

I may go to the concert. 我有可能去参加音乐会。

3. can

can 表示猜测时意为“可能”。

She can't be in the office now. 她现在不可能在办公室里。

考点三、几个情态动词的用法

1. shall

a. shall用于第一、三人称,表示征询对方意见。

Where shall I wait for you? 我应该在哪里等你?

b. 用于第二、三人称,表示命令、警告、强制、允诺。

You shall do as I say. 你应该按照我说的做。

Tell him that he shall have the book tomorrow. 告诉他他明天要把书拿来。

2. should

a. should 通常用来表示现在或将来的责任或义务,意为“应该,应当”。

You should complete your experiment on time. 你们应该按时做完你们的实验。

b. should 可以用来表示意外、惊喜或者在说话人看来是不可思议的,尤其在以why, who, how等开头的修辞疑问句或某些感叹句中,意为“竟会,居然”。

How should I know it? 我怎么会知道这件事?

c. should也有“按理推测”的含义,意为“理应……”。

He should be at home. 他应该在家。

3. need

a. need作情态动词时,一般用于否定句和疑问句中。

You needn't tell him about it because I have told him. 你不需要告诉他,因为我已经告诉过了。

b. need作实义动词时其后可以跟名词、代词、不定式、动名词等。

I need to buy a book. 我需要买一本书。

4. dare

a. dare作情态动词时,可用于否定句、疑问句和条件状语从句中。

She dare not stay alone. 她不敢一个人呆着。

b. 作实义动词时,dare常用在否定句和疑问句中,dare to do sth.中的to可省,但在肯定句中to不能省。

She doesn't dare (to) jump down from the wall. 她不敢从墙上跳下来。

He dares to do so. 他敢这么做。

考点四、表示请求的表达

1. can / could

can / could表示请求允许、拜托对方做事,但could的语气更委婉。

Could you tell me how to get to the post office? 你能告诉我邮局怎么走吗?

2. will / would

will用于第二人称的疑问句中,表示询问对方的意志,也可表示请求或建议,但would的语气更委婉。

Will you please spell his name for me? 请你把他的名字拼给我好吗?

3. shall

shall用于第一、三人称,表示征询对方意见。

Shall we go now? 我們现在可以走了吗?

4. may / might

may / might表允许或请求的意思,用might则语气更加委婉、客气。may 主要用于第一人称,而且要比用can正式得多。

May I use your phone? 我可以用你的电话吗?

二、名词性从句

考点一、连接词及从句类型

1. 从属连词

从属连词that, whether, if在句中只起连接作用,不作成分。that无意义,whether和if有意义,意为“是否”。

That he will come is certain. 他会来这件事情是确定的。(主语从句的that不可省略)

Whether she's coming or not doesn't matter. 她来不来不重要。(主语从句只能用whether不能用if)

I believe (that) they will finish the work. 我相信他们会完成工作的。(宾语从句,这里的that可以省略)

We haven't settled down the question of whether we should stay. 我们还没决定要不要留下来。(作介词的宾语时,只能用whether不用if)

The fact is that I have never been there. 问题在于我从来没有去过那里。(表语从句的that不能省略)

The question is whether it is worth doing. 问题在于是否值得做。(表语从句只能用whether)

The news that Luo Jing died made a lot of audience sad. 罗静死了的新闻让很多观众伤心。(同位语从句的that不能省略)

The question whether the work was worth doing has not been decided. 这份工作是否值得做还没有被决定。(同位语从句只能用whether)

2. 连接代词

连接代词who, whom, whose, which, what有各自的意义,在从句中作主语、表语、宾语或定语。

Whose father will come is not known yet. 谁的爸爸会来还不知道。(主语从句,whose作定语)

I really don't know which dress I'll buy. 我不知道要买哪条裙子。(宾语从句,which表示“哪一个”)

That is what we've been expecting. 那是我们一直期望的。(表语从句,what表示事情或者东西)

I had no idea who had stolen the money. 我不知道谁偷了这笔钱。(同位语从句,who指代人,可作主语或宾语)

3. 连接副词

连接副词where, when, why, how有各自的意义,在从句中作状语。

Where she has gone is not known yet. 她去了哪里还不知道。(主语从句,where引导地点状语)

I don't know when we are going to have the meeting. 我不知道我们什么时候开会。(宾语从句,when引导时间状语)

This is why he is late. 那是他迟到的原因。(表语从句,why引导原因状语)

I have no idea how he will go there. 我不知道他会怎么去那里。(同位语从句,how引导方式状语)

考点二、比较that, why和because引导表语从句

1. reason后的表语从句要用that引导,即The reason why... is that...,意为“……的原因是……”。

The reason why I'm so late is that I missed the bus. 我迟到是因为我错过了公交车。

2. why引导表语从句时说明由上述原因导致某种结果,即前面说明原因,后面说明结果。

That's why I'm so late. 那是我为什么那么迟的原因。

3. because引导表语从句时说明产生上述结果的原因,即前面是结果,后面是原因。

That I'm so late is because I got up late. 我迟到是因为我起床迟了。

考点三、what 的用法

在名词性从句中,what除了可以指代事情和东西以外,还可以表示“……的人或样子”、“……的时间”、“……的地方”等,在从句中充当主语或者宾语,而where和when则只能作状语。

1. 表示“……的东西或事情”

They've done what they can to help her. 他们已经尽力帮助了她。

2. 表示“……的人或样子”

He is no longer what he was. 他已经不是以前的那个样子。

3. 表示“……的数量或数目”

Our income is now double what it was ten years ago. 我们现在的收入是10年前的两倍。

4. 表示“……的时间”

After what seemed like hours he came out with a bitter smile. 似乎过了几个小时他才苦笑着出来。

5. 表示“……的地方”

This is what they call Salt Lake City. 这就是他们称为盐湖城的地方。

考点四、it的用法

1. it 作形式主语

为了保持句子平衡,常把主语从句后置,而用it作形式主语,常用的结构有“It +系动词+形容词(important / possible / necessary / likely...) +that从句”,“It+系动词+冠词+名词(fact / idea / honor / pity / question...)+that从句”,“It+系动词+过去分词(said / known / proved / suggested / thought...)+that从句”,“It+特殊动词(appear / happen / seem...)+that从句”。

It's important to protect the environment. 保护环境很重要。

It's a pity that you can't come. 很遗憾你不能来。

It is said that he has arrived in Beijing. 据说他已经到北京了。

It seemed that Mr. Green was unhappy. 格林先生好像不开心。

2. it 作形式宾语

appreciate, like, hate, dislike, love, enjoy, prefer等动词带宾语从句时,后要用it来作形式宾语,it后接由if或when引导的从句为真正的宾语,it没有任何意思,但不能省略。

I hate it when they talk with their mouth full of food. 我讨厌人们满嘴食物的时候聊天。

I would appreciate it if you could help me. 如果你能幫我我将不胜感激。

考点五、doubt的用法

doubt用在肯定句中,其后通常接whether / if引导的宾语从句;在否定句中或疑问句中通常接that从句。

I doubt if / whether he'll come. 我怀疑他是否会来。

I don't doubt that he will succeed. 他会成功的,这点我毫不怀疑。

考点六、在名词性从句中一律用陈述句的语序,即使从句表达的是疑问含义。

The problem is what he has done to the little boy. 问题是他对那个小男孩做了些什么。

猜你喜欢

肯定句同位语否定句
同位语从句讲与练
can have done用法小结
学写双重否定句
虚拟语气“本……”的表达方式和高考
重点词语辨析与演练
must,have to和have got to
Units 1—2句型转换专练