条件状语从句-初二英语

2015-12-20

条件状语从句

1、定义

由引导词if或unless引导的状语从句叫做条件状语从句。在英文中，条件是指某一件事情实现之后(状语从句中的动作)，其它事情(主句中的动作)才能发生，通常译作"假如"。(注意:在含有条件状语从句的复合句中，表示将来时态，主句是一般将来时态,祈使句或谓语动词是情态动词，从句要用现在时态,即[主将从现原则]。

Eg1: Take the medicine, you will be fine.

Eg2: If you can read as many English books as possible, your English will be improved.

2、用法

语法引导条件状语从句最常用的连词是if, 由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引导的条件状语从句既可以将从句放前面也可以将从句放后面。除了if 之外，还有其他连词也可以引导条件状语从句。

【注：在条件状语从句中，绝大数情况下some要变为any。】

(1) unless conj.除非，若不，除非在……的时候

Eg1: You will fail to arrive there in time unless you start earlier.如果你不早点动身，你就不能及时赶到那儿。

Eg2: Unless it rains, the game will be played.除非下雨，比赛将照常进行。

(2) on condition(that)...在……条件下，如果on condition (that)...引导的条件从句是主句事件发生的前提条件或唯一条件。

Eg1: I can tell you the truth on condition that you promise to keep a secret.我可以告诉你真相，条件是你答应保密。

Eg2: You can go swimming on condition (that) you don't go too far from the river bank.你只有在不远离河岸的条件下才可以下水游泳。

Attention（注意）：

①unless = if...not. Eg: Let's go out for a walk unless you are too tired.

If you are not too tired, let's go out for a walk.

②if 引导的条件句有真实条件句和非真实条件句两种：

真实条件句Eg：If it rains tomorrow, we won’t go on a park

非真实条件句是虚拟语气的一种，表示与事实相反，主句用would do，从句用过去式，具有假设性，一定不会是真的,即所假设的事情基本不会有发生的可能。

Eg：If I were you, I would go with him.

③so/as long as （只要）、in case（万一）引导。

Eg1: So long as you’re happy,it doesn’t matter what you do. 只要你高兴，你做什么都没有关系。

You may borrow my book as long as you keep it clean只要你保持书的清洁，你就可以把我的书借去。

Eg2: Take your umbrella in case it rains. 带着你的伞吧，以防下雨。

④“祈使句+and / or+简单句”。其中and表示句意顺承；or则表示转折，意为“否则”。

Eg1:If you work harder, you’ll pass the exam.

= Work harder, and you’ll pass the exam. 如果你再努力些，你就会通过考试。

Eg2: If you don’t hurry up, you’ll miss the train.

= Hurry up, or you’ll miss the train. 如果你不快点儿，你就赶不上火车了。

3、练习题Ⅰ.单项选择

1 .If you _____ to the party, you’ll have a great time.

A. will go

B. went

C. go

D. going

2. It will be a long time ____ Peter _____ his work.

A. since, has finished

B. after, finishes

C. when, will finish

D. before, finishes.

3. What will father _____ us from Japan?

A. take

B. bring

C. carry

D. make

4．I ____ her the answer if she ____me.

A. can tell, will ask

B. will tell, will ask

C. would tell, ask

D. will tell, asks

5. – What are you going to do tomorrow? --We’ll go to the library tomorrow if it ____.

A. isn’t rain

B. rain

C. won’t rain

D. doesn’t rain

6.—Do you know when he will come back tomorrow? --Sorry, I don’t know. When he ____ back, I’ll tell you.

A. comes

B. will come

C. come

D. may come

7. What will you do if yo u _____ to the old folk’s home visit?

A. go

B. went

C. going

D. will go

8. If I eat ____ food, I’ll be very fat.

A. too many

B. many too

C. too much

D. much too

9. I’ll give the book to him if he ___ here next Sunday.