if引导的条件状语从句知识点及练习题

if引导的条件状语从句（一）定义 if引导的句子在复合句中表示条件，假如if从句的动作发生，主句的动作就（不）会 发生，因此称为条件状语从句。（二）位置 if 引导的条件状语从句位置灵活，可直接放在主句后面，也可以放在句首。放在句首 时，从句后面要用逗号和主句隔开。 If I have enough money, I will travel around the world. I will travel around the world if I have enough money.（三）用法（1）当主句是一般将来时时，从句用一般现在时。（主将从现）构成条件从句主句时态If+一般现在时主句+shall/will+动词原形例句 If it rains tomorrow, well stay at home（2）当主句是祈使句时，从句也用一般现在时。 Work hard, and youll pass the exam easily. 努力学习，你将很容易通过考试。 If you work hard, youll pass the exam easily. Hurry up, or youll miss the train. 快点儿，否则你就赶不上火车了。 If you dont hurry up, youll miss the train. （3）当主句含有情态动词时，if引导的条件状语从句通常用一般现在时。 We must study hard if we want to pass the final exam. 如果想通过期末考试，我们必须努力学习。（4）用含介词with或without的介词短语转换。 If you help me, Ill finish my job soon. With your help, Ill finish my job soon. 如果你帮我，我将很快完成我的工作。 If there is no water, fish cant live. Fish cant live without water. 离开水，鱼不能生存。 （四）if引导的条件状语从句与if引导的宾语从句的区别 if引导宾语从句时表示“是否”，位于及物动词之后； if引导的条件状语从句时表示“假如，如果”，位于句首或句中。 I dont know if he will come tomorrow. If he comes, Ill call you.练习一、选择题1. _ you dont go to bed earlier, you will feel tired in the morning. A. Unless B. If C. Though D. Until2. Why not look up the new word in a dictionary _ you dont know it? A. if B. that C. though D. whether3. Talk to your teacher and you will get help _ you have a problem. A. unless B. if. C. until D. so4. I wont go to tomorrows party _ Im invited. A. if B. unless C. when5. The children will climb the hill if it _ tomorrow. A. wont rain B.didnt rain C. isnt raining D. doesnt rain6. We wonder if our teachers _ to our graduating party next weekend. If they_, well be very happy. A. will come; will come B. come; will come C. will come; come D. come; come二、翻译句子。1. 如果明天下雨，我们将在家看电视。 Well stay at home watching TV if it _ （rain）tomorrow.2. 如果她早点起床，就有时间在家里吃早餐. If she _ _ a little earlier, she ll have time to eat breakfast at home. 3. 如果你参加聚会，你将会过得很开心。 If you _ the party, you _ _ a great time.4. 如果你经常听英文歌，你将会喜欢英语。 If you often _ _