六年级上册第一二单元的知识要点

六年级上册第一、二单元知识要点

语法知识：

1. 祈使句：

表示请求、命令、劝告、建议、号召等的句子，常省略主语you，句首用动词原形。

肯定祈使句：动词原形+其他成分

Listen to me carefully.

否定祈使句：Don't ( never ) +动词原形+其他成分

Don't be late for class next time.

Don't do that again.

Never leave today's work for tomorrow.

Let引导的祈使句：Let+第一、三人称+(not)动词原形，表示建议做某事。

Let me try again. Let Jack wait a minute.

祈使句的特殊用法：

No +名词/动名词+其他

No swimming!

祈使句+and+简单句，表示“如果...就...”

Go down the street, and you'll see a cinema.

祈使句+or+简单句，表示“...否则...”

Be quick, or we'll be late.

在祈使句后面，加一个问句，使语气更加委婉。

Don't tell anyone, will you?

祈使句的反意疑问句：

Sit down please, will you ?

Don't smoke in the meeting room, will you?

不论祈使句是肯定句还是否定句，其简单问句都用"will you?"

Let's go skating, shall we?

Let's not watch TV before supper, shall we?

Let us go shopping, will you?

2. 情态动词：

表示说话人的情绪、态度或语气的动词叫情态动词。情态动词本身有一定的词义，但它也和助动词一样，不能单独作谓语，情态动词后必须跟动词原形。

情态动词的语法特征：

A.不能表示正在发生或已经发生的事情，只表示期待或估计某事的发生。

B.没有人称和数的变化；也没有不定式、分词等形式。

C.除ought和have 以外，后面只能接动词原形。

D.need和dare等既可以做情态动词，也可以做行为动词。

need 作情态动词：

①表示必须，主要用于否定句和一般疑问句中。

You needn't worry about him.

②回答由need提出的一半疑问句时，肯定用must，否定用needn't.

Need I finish my homework today? Yew, you must./ No, you needn't.

need作行为动词：

①need to do

You don't need to tell me the truth.

否定形式根据时态和人称用相应的主动词。

They said that they needed to go there on time.

must : 否定式mustn't

①must表示自己的主观看法或要求别人必须做某事。意为“必须”、“应该”。

We must learn English hard.

②must表示推测，意为“准是、一定”一般指可能性很大。

The woman must be Li Lei's mother.

③must表示推测时，其否定式不用mustn't,而用can't.

The door is closed. He can't be at home.

④mustn't表示“不可以”、“禁止”。

You mustn't play on the road.

⑤以must开头的疑问句，肯定回答用must,否定回答用needn't,意为“不必”。

Must we come to the party early?

Yes, you must. / No, you needn't.

⑥must与have to的区别：must表示主观的看法，have to表示客观的需要。must只有一种形式，而have to 有多种形式。第三人称单数现在时用has to,过去时用had to, 将来时态用will have to.

3. 词性转化：

care -- careful （反）careless -- carefully （反）carelessly

a./n. adj. adj. adv. adv.

act -- actor --active --actively -- activity

v. n. adj. adv. n.

noise -- noisy -- noisily

n. adj. adv.

quiet -- quietly

adj. adv.

4. 易混词辨析：

①cross, across, through

cross 动词

across 介词“从一边到另一边”Go across the road.

through 介词“从中穿过”Go through the park.

②sometimes, sometime, some time, some times

sometimes: adv. （频度副词）有时

He sometimes comes to see me.

sometime :adv. 在某时（不确切或尚未确定）

She will clean her room sometime next week.

some time: 一段时间

Tom will stay with me for some time this summer.

some times:几次

My mother calls me some times every week.

③all , whole

修饰单数名词或抽象名词时，它们可以互换，但次序不同：all放在the,this, that, my, your 等词之前，whole则放在之后。