条件状语从句讲解(基础版本)演示教学

条件状语从句讲解

――if引导的条件状语从句（注意&练习）在句子中做条件状语的从句称为条件状语从句。可置于句首、句尾，有时还可置于主语和谓语之间。引导条件状语从句的连接词有：if ,unless,as/so long as等

1.if引导的条件状语从句

表示在某种条件下某事很可能发生。

If we pay much attention to the earth, we'll have a better world.

如果我们多关爱地球，就会拥有一个更美好的世界

If it rains tomorrow, what shall we do?

如果明天下雨，我们怎么办？

注意：if还可以引导虚拟条件句，表示不可实现的条件，从句中多用一般过去时或过去完成时。What would happen if there were no water ?

如果没有水会怎样？

2.unless引导的条件状语从句

unless的意思是如果不，除非。可与if...not互换。

You will fail in English unless you work hard.

你英语考试会不及格的，除非你更加努力。

3.as /so long as引导的条件状语从句

as /so long as意思是“只要”

So long as you're happy,i will be happy.

只要你高兴，我就高兴。

4.once引导的条件状语从句

once引导的条件状语从句，意为“一旦...，就”，从句可置于主句前或后

Once you begin,never stop.

一旦开始，就绝不要停止

Maths is easy to learn once you understand the rules.

一旦你理解了规则，数学就不难学了。

提示：在条件状语从句中，用一般现在时代替一般将来时，用一般过去时代替过去将来时。

If the weather is bad next week, we'll put off the climbing.

如果下周天气不好，我们将推迟爬山。

Father told me if I worked hard he would buy me a gift.

爸爸告诉我，如果我努力学习，他会给我买一份礼物。

注意：

学习" if " 引导的条件状语从句的用法,现在总结一下:

if 条件句不一般,几个要点记心间;

条件句,放在前,逗号要放句中间。

条件句表可能，主句多用将来时；

条件句表事实，主句常用现在时。

在if 引导的条件状语从句中，如果从句谈论的是一个有可能发生的事实及其产生的相关的结果，主句用一般将来时态，从句用一般现在时态。如：

We can walk there if we can't find a bus .

If it rains tomorrow ,we will not go to the zoo.

What will you do if you find a panda in danger.

如果if 条件句谈论的是重复发生和预示要发生的情景和事件，则主从句大多用一般现在时态。如：If bears are in danger ,they attack people.

在if 引导的条件状语从句中，if 和条件句位置灵活，可直接放在主句后面，若if 条件句放句首，从句后面要加逗号，和主句隔开。还要注意前后时态一致原则

if 条件状语从句的时态练习

一．在正确的答案下划一条线。

1.Daina ( will go/go/goes) to Europe if she (will pass/pass/passes) the exams .

2. The graduates (will teach/teach/teaches) in the poor village if the Ministry of Education (will agree/ agree/agrees) soon.

3. If there (will be/ are/is) a car accident, they (will call/call/calls) 110 for help at once.

4. If it (won’t/don’t/doesn’t/ isn’t) rainy, we (will take/ take/takes) walk outside.

5. If a UFO (will land/land/lands) in front of me, I (will go/go/goes) in to look for the alien.

6. If he (will have/have/has) money, he (will bulid/build/builds) a science lab.

7.Don’t wait for me if I (am/ will be) late.

8.They (won’t/don’t) go to the beach if it (will rain/rain /rains).

9. I (will call/ call) you if he (will stay/stay /stays) at home.

10. Mr Smith (will let/ let/lets) you know if he (will need/ need/ needs) help.

11. (Will / Do/ Does) he visit the museum if he (won’t / don’t/ doesn’t) get tired?

12. Where (will/ do/does) they live if they (will miss/ miss/ misses) the bus?

状语：状语是句子的重要修饰成分。状语是谓语里的另一个附加成分,它附加在谓语中心语的前面,从情况,时间,处所,方式,条件,对象,肯定,否定,范围和程度等方面对谓语中心进行修饰或限制。用来说明地点、时间、原因、目的、结果、条件、方向、程度、方式和伴随状况等。

状语一般由副词、介词短语、分词和分词短语、不定式或相当于副词的词或短语来担当。其位置一般放在句末，但也可放在句首或句中。

副词是一种用来修饰动词,形容词,副词或全句的词,说明时间,地点,程度,方式等概念。

1.副词一般在句子中做状语．

He speaks English very well. 他英语说得非常好.中的very是程度副词，用来修饰well。very well是修饰speak的程度状语。

He is playing under the tree.他在树下玩儿.中的under the tree 是地点状语.

2. 不定式在句子中可以作目的状语。

I come specially to see you.我专门来看你.

3.介词短语

Ten years ago, She began to live in Dalian.

The boy was praised for his bravery.

4.从句作状语

When she was 12 years old, she began to live in Dalian.

If I am not busy tomorrow, I will play football with you.

5.分词作状语

Having had a quarrel with his wife, he left home in a bad temper。

Inhibited in one direction, it now seems that the Mississippi is about to take another.

在复合句中，由从句表示的状语叫做条件状语从句。它可以用来修饰主语中的动词.形容词.副词等。根据它表达的意思，状语从句可以分为时间状语从句，原因状语从句，条件状语从句，比较状语从句，目的状语从句，结果状语从句和让步状语从句等。

定义

由连接词if或unless引导的状语从句叫做条件状语从句。（注意：在含有条件状语从句的复合句中，如果主句是一般将来时态，从句要用一般现在