1、till/until引导的时间状语从句,1.肯定句：till/until直到 表某动作一直持续到某时间才停止 （主句的谓语动词时延续性动词） eg: I have to stay here until the rain stops.I watched TV until my mother returned last night.,2.否定句 notuntil 直到才 (not 可以用表示否定意义的词代替，比如 never, nothing, seldom等) 表示某动作一直持续到某时间才开始 （主句的谓语动词是非延续动词） eg：He wont go to bed till/until she
2、 returns.Tom knew nothing about it untill his I told him.,注意 1.till 不可以置于句首，until可以 eg: Until the class is over I read the book. 2.not until 在句子开头时要用倒装 Not until you told me did I know the truth.,2. I will not go out_I finish my homework. A.until B.while C. since D.but,3. Ill wait_she comes out. A.w
3、hether B.afterC.though D.until,if 和unless引导的 条件状语句,真题 1.Tom knew nothing about it_ his sister told him. since B. if C. until(湖南中考）,常考的状语从句主要是， 1. when,while,as,until,not until等引导的时间状从 2. so, that, so（）that, such（） that 等引导的结果状从 3.if，unless等引导的条件状从,由if引导的条件状语从句，if意为“如果”, 表示在某条件下，某事就很可能发生。,。,If it sto
4、ps snowing ，we can go out. 如果雪停了，我们就可以出去。,If it snows tomorrow, we will build a snowman. 如果明天下雪，我们将去堆雪人。,If引导的条件状从的时态 1.从句用一般现在时，主句是一般将来时主将从现,If it is fine tomorrow, we will go on a ship. 如果明天天气好，我们就去旅行。,2. 用if条件句表达客观真理或普遍现象，主从句时态均用一般现在时. 即主现从现例. If you freeze water, it turns into ice. 如果你冷冻水，它将变成冰。
5、A fish dies if you take it out of water.如果你把鱼拿出水，它就会死掉。,注意 ： 在 if 引导的条件状语从句中，if 条件句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。 If I get up late, I will be late for school. =I will be late for school if I get up late. 如果我起床晚了，我就会迟到。,unless引导的条件状语从句,unless 是 if 得反义词，相当于 if not,表“如果不，除非”. If you dont work h
6、ard, you will fail. =Unless you work hard, you will fail. 如果你不努力，你就会失败。 除非你努力，否则你就会失败。,真题回顾,We will have no water to drink we dont protect the earth. A.until B.before C. though D.if (2010,上海,37),（如果我们不保护地球，我们将没有水喝。）,2.Bob promise to join in the football match he has to help his parents on the farm.
7、A.if B. as C. unless D. when(2010,安徽，35）,3（01 上海）You will succeed in the end_ you give up halfway. A even if B as though C as long as D unless,Thank you!,GOODBYE!,例句： 1.Unless it rains, I will go home on foot. 如果不下雨，我将走回家。,2.Dont touch the instruments unless the teacher allows you 如果没有老师的允许，不要乱动仪器。,
8、2.if从句用一般现在时，主句用may/might/can,If I finish my homework, I can play basketball. 如果我昨晚作业，我就可以打篮球了。,3.if从句用一般现在时，主句用must/should,If you want go to a good university, you must study hand. 如果你想上好的大学，你必须努力学习。,The sports meeting wont be,2.Dont touch the instruments unless the teacher allows you 没有老师的允许，不要乱动仪器。,If I have enough money,I will travel around the world.,I will go to a good university.,If I study hard,
