3 because：因为，连接原因状语从句

She didn't go there，because she was ill.

因为她病了，所以她没去那儿。

1.回答Why问句时，只能用because，不能用for或 as.

Why are you late?

你为什么迟到?

Because I met a traffic accident on my way here.

因为在我来这儿的路上，遇到了车祸。

2.汉语中，我们经常说因为……所以，但在英文中有了because，就不能再用so。

(×)Because he was tired， so he couldn't walk there.

因为他累了，所以他不能走到那儿了。

4 if，though (although)

If it doesn't rain，we'll go to the park.

如果不下雨，我们就去公园。

Though I was tired， I still worked hard.

虽然我很累，可是我仍然努力地工作。

1.if：如果(引导条件从句)

You can pass the exam if you study hard.

如果你努力学习，你会及格的。

2.though，although：虽然(引导让步状语从句)和原因状语从句一样，如果用了though，although (虽然)就不能再用but(但是)。

Although(Though) I live near the sea， I'm not a good swimmer.

=I live near the sea，but I'm not a good swimmer.

虽然我住在海边，可是我游泳并不好。

注意

注意时态一致，和时间状语从句一样。主句是将来时之时，从句要用一般现在时。

5 so…that：太……以致……

He is so old that he can't work. = He is too old to work.

他太老了，不能工作。

The box is so heavy that I can't lift it.

=The box is too heavy for me to lift.

箱子太沉了，我抬不起来。

The girl is so beautiful that everybody likes her.

这个小女孩太漂亮了，每个人都喜欢她。

注意

注意此句型与too…to的互换。

so…that在肯定句中不能转换成too…to…。

三 连词比较

I　and 与or

1) 并列结构中，or通常用于否定句，and用于肯定句。

2) 但有时and 也可用于否定句。请注意其不同特点：

There is no air or water in the moon.

There is no air and no water on the moon.

在否定中并列结构用or 连接，但含有两个否定词的句子实际被看作是肯定结构，因此要用and。

典型例题

---I don't like chicken ___ fish.

---I don't like chicken, ___ I like fish very much.

A. and; and　 B. and; but　C. or; but　D. or;and

答案C。否定句中表并列用or, but 表转折。

判断改错：

(错) We will die without air and water.

(错) We can't live without air or water.

(对) We will die without air or water.

(对) We can't live without air and water.

3 )表示选择的并列结构

(1) or　意思为"否则"。

I must work hard, or I'll fail in the exam.

(2) either…or　意思为"或者……或者……"。注意谓语动词采用就近原则。

Either you or I am right.

判断改错：

(错) They sat down and talk about something.

(错) They started to dance and sang.

(错) I saw two men sitting behind and whisper there.

(对) They sat down and talked about something.

(对) They started to dance and sing.

(对)I saw two men sitting behind and whispering there.

解析：

第一句： and 连接两个并列的谓语，所以 talk 应改为 talked。

第二句：and 连接两个并列的动词不定式，第二个不定式往往省略to，因此sang 应改为 sing。

第三句：and 连接感观动词saw 后面的用作的宾补的两个并列分词结构，因此whisper应改为whispering。

注意：and 还可以和祈使句或名词词组连用表示条件。(or也有此用法)

Make up your mind, and you'll get the chance.

= If you make up your mind, you'll get the chance.

One more effort, and you'll succeed.

= If you make one more effort, you'll succeed.

II　but表示转折，while表示对比。

Some people love cats, while others hate them.

典型例题

--- Would you like to come to dinner tonight?

--- I'd like to, ___ I'm too busy.

A. and　 B. so　 C. as　 D. but

答案D。but与前面形成转折，符合语意。而表并列的and，结果的so，原因的as都不符合句意。

III so, therefore

He hurt his leg, so he couldn't play in the game.

注意：

a. 两个并列连词不能连用，但therefore, then, yet.可以和并列连词连用。

You can watch TV, and or you can go to bed.

He hurt his leg, and so / and therefore he couldn't play in the game.

b. although… yet…，但although不与 but连用。

(错)　Although he was weak, but he tried his best to do the work..

(对)　Although he was weak, yet he tried his best to do the work.

IV 比较so和 such

其规律由so与such的不同词性决定。such 是形容词，修饰名词或名词词组，so是副词，只能修饰形容词或副

词。so 还可与表示数量的形容词many，few，much， little连用，形成固定搭配。

so + adj.　　　　　　　　　such + a(n) + n.

so + adj. + a(n) + n.　　　such + n. (pl.)

so + adj. + n. (pl.)　　　 such +n. (pl.)

so + adj. + n. [不可数]　　such +n. [不可数]

so foolish　　　　　　　　 such a fool

so nice a flower　　　　　 such a nice flower

so many/ few flowers　　　 such nice flowers

so much/little money.　　　such rapid progress

so many people　　　　　　 such a lot of people

so many 已成固定搭配，a lot of 虽相当于 many，但 a lot of 为名词性的，只能用such搭配。

so…that与such…that之间的转换既为 so与such之间的转换。

Eg :The MP3 cost me ________ money that I ccouldn't afford to buy it .

A .so much .B .such much C .so many

D . such many .(Key :A )