楊慶春
一、條件狀語從句句型
條件狀語從句表示主句動作發(fā)生的條件, 引導條件狀語從句的連接詞有:if,意為“如果;假設”;unless,意為“如果不;除非”。if從句可放在主句前或主句后,從句置于主句前時,須用逗號與主句隔開,反之則不用逗號。
1. if從句,主語+will(not)+動詞原形,在此句型中,從句談論的是一個可能發(fā)生事實的條件,主句表示其產(chǎn)生的相應結(jié)果。
If you ask him, he will help you. 如果你請他幫忙,他會幫助你的。
If it doesn’t rain, we’ll go to the Great Wall. 如果明天不下雨,我們就去長城。
2. if從句+祈使句,在此句型中,從句表示能夠發(fā)生或可能發(fā)生的事情(如果……),主句表達建議(就……)。此時,從句謂語動詞要用一般現(xiàn)在時態(tài)。
Please ring me up if you have time this evening. 如果你今晚上有空的話,請給我打電話。
If you want to go, please let me know. 如果你想要去,請讓我知道。
3. if從句,主語+may(can, might, could…)+ 動詞原形,在此句型中,從句表示能夠發(fā)生或可能發(fā)生的事情,主句表達主觀上能夠或者應該做什么。
If it stops snowing, we can go out. 如果雪停了,我們就可以出去了。
If you want to lose weight, you should take more exercise. 你要想減肥,就應該多運動。
二、條件句與簡單句的關(guān)系
句型:祈使句+and (or, then)+簡單句(用一般將來時),這種句型相當于if引導的一個條件狀語從句。從意義上可以看出祈使句表示一種條件或假設,陳述句表示一個結(jié)果。因此這個句型通??梢赞D(zhuǎn)換成“if條件狀語從句+主句”形式。
1. 祈使句與簡單句之間常有一個逗號,如果表示順承關(guān)系,用and連接前后句。and后面的簡單句中謂語動詞常用將來時,主語通常是you,也可用其他人稱。改寫成if條件狀語從句時要去掉and。
Study hard, and you will pass the exam. 努力學習,你會通過考試的。
=If you work hard, you will pass the exam.
2. 如果表示轉(zhuǎn)折關(guān)系則用or。or意為“否則”,表示從反面來預測一個結(jié)果。因此,需要把if條件句變?yōu)榉穸ň湫问?,這樣意思才能完整。
Work hard, or you won’t pass the exam. 你要是不努力學習,考試就不會及格。
= Work hard, and you will pass the exam.
= If you work hard, you will pass the exam.
= If you don’t work hard, you won’t pass the exam.
Hurry up, or you’ll be late. =If you don’t hurry up, you’ll be late.
3. 祈使句+ then+ 簡單句,這種句型中的then不是并列連詞,而是連接副詞,改寫成if條件狀語從句時要去掉then。
Use you head, then you’ll find a good way. 動腦,你會找到一個好的方法。
= If you use your head, you’ll find a good way.
Go into the cave, then they won’t see you. 進入洞穴,他們不會看見你的。
= If you go into the cave, they won’t see you.
4. 介詞with或without表示假設關(guān)系時,可以改寫成if條件狀語從句。
Without water, nothing could live. 沒有水,就沒有生命。
= If there ware no water, nothing could live.
With your help, I’ll certainly be good at physics.
= If I have your help, I’ll certainly be good at physics.
小練習:用if 連接下面的句子。
1. You do not understand the article. Please ask your teacher.
2. You want to know more about it. Please call your teacher.
3. Tell him to make a phone call to me. He will come here tomorrow.
4. You want to go. Please tell me.
5. We will have no water to drink. We don’t protect the earth.
Keys:
1. If you do not understand the article, please ask your teacher.
2. If you want to know more about it, please call your teacher.
3. If he comes here tomorrow, tell him to make a phone call to me.
4. If you want to go, please tell me.
5. If we don’t protect the earth, we will have no water to drink.