英语语法基础-第9讲(副词性从句)课件.pptVIP

英语语法基础 第九讲 副词性从句 ——状语从句 状语从句就是在复合句中起状语作用的从句。 状语从句可以用来修饰动词（谓语动词或其他非谓语动词）、定语、状语，甚至整个句子。 根据状语从句在句中的具体作用可以分为时间、地点、原因、目的、结果、条件、让步、方式、比较等状语从句。 状语从句可以位于句首、句中或句尾。位于句首时，句末通常有逗号与主句隔开；位于句中时，从句前后须有逗号；位于句尾时，从句的前面可以不用逗号。通常，比较、方式和结果状语从句位于主句之后。 状语从句一般由一个连词引导，也可由一些起连词作用的短语结构引导。 一、时间状语从句 时间状语从句说明动作或状态发生、存在的时间。时间状语从句可以由下列连词或词组引导。下面分别举例介绍这四类连词或词组。 一、时间状语从句 A. when等 As time goes by, the pollution in this river is getting more and more serious. Whenever she had a cold, she ate only fruit. 注：时间状语置于句首时，后面要有逗号与主句分开。 B. before等 He will go to study abroad after he graduates from the college. I have not seen him since he left the company. 注：until 经常与not连用，not…until表示一个固定意思，直到…才。 He didn’t announce the news until he was sure of it. Go straight ahead until/till you reach the post office. 注：在时间状语从句中，不用将来时。 一、时间状语从句 C. as soon as等 We will leave the minute he is ready. Every time he comes to see us, he brings us some candies. D. hardly…when 等：hardly…when, scarcely…when，no sooner…than的意思一样，但在使用时，要注意它们的搭配。hardly，scarcely分别和when连用，no sooner和than连用，不能调换。 I had hardly sat down when the telephone rang. 注：hardly，scarcely，no sooner位于句子开头时，句子的主、谓语要倒装。 Scarcely had the noise died away when someone started to laugh again. 二、地点状语从句 地点状语从句说明动作或状态发生、存在的地方。地点状语从句由where （在…的地方）和wherever（无论在…的地方）引导。 Keep the medicine where children cannot see it. You can camp wherever you like these days. 三、条件状语从句 条件状语从句说明动作或状态发生、存在的条件。条件状语从句由下列连词或词组引导。下面分别举例介绍这三类连词或词组。 三、条件状语从句 A. if 和unless We shall have a picnic if it is a fine day tomorrow. I’d like to go swimming unless the water is too cold. = I’d like to go swimming if the water is not too cold. B. as (so) long as 等 As long as we don’t lose heart, we’ll find a way to overcome the difficulty. In case the car burns down, we’ll get the insurance money. C. suppose/supposing 等 Supposing he doesn’t agree, what will you do? Providing there is no objection, we shall make a decision. 注：在条件状语从句中，不用将来时。 四、原因状语从句 原因状语从句说明动作或状态发生的原因。原因状语从句由because（因为），since（因为），as（因为），n