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Unit 5 Rhythm 语法篇____________________________________________________________________________________________________________________________________________________________________1、状语从句（I）—时间和让步2、状语从句（II）—原因，结果和目的在复合句中修饰主句或主句中的某一部分作状语的从句叫状语从句。
状语从句通常由从属连词或起连词作用的词组引导。
状语从句根据它表达的意思不同，可分为时间、地点、原因、目的、结果、条件、方式、比较、让步九类。
一，时间状语从句：主要由when, whenever, after, before, as, (ever)since, as soon as, (not) until, while,immediately, the moment等连词引导。
1.when, while, as（当…时）的用法区别①当主句谓语动词表示短暂动作，从句中的谓语动词有持续性特征时，这三者可以互换。
例：I got the news on the radio when/while as/ I was having breakfast.②当主，从句的谓语动词都表示非持续性动作，而且两个动作几乎同时发生时，不用while, 可用when和as。
例：I met as/when I was getting off the bus.③当从句的动作发生在主句的动作之前，只能用when引导从句，不可用as或while。
例：When you have finished your work, you may have a rest.④当主句谓语动词是be doing/be about to do/had done时只能用when, when在此时相当于and at that moment就在那时。
例：They were watching the World Cup when suddenly the lights went out.⑤当主、从句的动作同时发生时，或表示对比关系，用while。
例：She thought I was talking about her daughter, while in fact, I was talking about my daughter.⑥as表示“随着”例：As time goes on, it’s getting warmer and warmer.2.表示“一…就…”的结构Hardly/scarcely…when, no sooner…than和as soon as例：I had hardly/scarcely got home, when it began to rain.I had no sooner got home than it began to rain.As soon as I got home, it began to rain.注意：如果hardly, scarcely或no sooner置于句首，句子必须用倒装结构。
例：Hardly/Scarcely had I got home when it began to rain.3.比较until和till①until/till用于肯定句时，表示“直到…为止”，主句必须为持续性动词。
例：We shall wait until/till he comes.②not until/till表示“直到…才”，主句通常要用短暂性动词，这时until和till可用before代替。
例：I didn’t leave until/till/before she came back.③当not until位于句首时，主句中的主语，谓语要使用倒装语序。
例：Not until she stopped crying did I leave.注意：until引导的从句可以放在主句之前或主句之后，但till从句一般不放在句首。
4.名词词组引导的时间状语从句，如：every time（每次），the next time（下次），the moment（一…就），the instant（一…就），the second（一…就），the day（那天）等。
I didn’t have a penny the last time I saw you.5.since和before的用法比较：两者均可用于“It + be…+since/before+从句”的句型。
区别是since表“自从…以来”，其结构是：It is/has been some time since sb. did sth.; It was some time since sb. had done sth.。
而before的含义是“过了多久才…”，结构是：It will be some time before sb. do(es) sth.; It was/had been some time before sb. did sth.。
例：It is three years since he joined the army.二，让步状语从句让步状语从句表示在某种相反的条件下，主句中的情况依然会出现。
让步状语从句由although, though, as, while, however, whatever, whoever, whomever, whichever, whenever, wherever, whether…or…, no matter(who, what, etc), even if, even though等词或短语引导。
①although/though这两个词意思是一样，都意为“虽然，尽管”。
although比though正式。
although, though 不能与but连用，但是可以与yet, still, nevertheless连用。
而while突出主句和从句的对比。
例：Although/Though he blames me, yet I will trust him.②even if, even though这两个词语气比though, although强，意为“即使”，两者可以通用。
例：We won’t be discouraged even if/though we fail ten times.③however, whatever, whenever, wherever相当于no matter(how, what, when, where, etc)，这几个词引导的让步状语从句语气十分强烈。
No matter how busy he was, he studied English every day.④连词as同though一样，也可以引导让步状语从句，但从句中要用特殊语序。
例：Children as he is, he knows a lot.三，原因状语从句原因状语从句是表示原因和理由的从句。
引导原因状语从句的有as, because, since, now(that), considering that, seeing that等。
①because, since, as, for的区别because语气最强，表示产生某结果的直接原因，一般置于主句之后，也可以放在主句之前，用逗号隔开，在回答why引导的特殊疑问句时，只能用because。
例：You shouldn’t get angry only because some people speak ill of you.since往往表示的是已知的客观事实，或分析后的推理，引导的从句大多置于句首，语气比because 弱。
例：Since you’re not interested, I won’t tell you about it.as表示的理由最弱，只是对主句的附带说明，重点在主句。
as从句通常放在主句前。
例：As you are unable to answer, perhaps we should ask someone else.for是并列连词，只用于连接表示原因的分句，因此不能用于句首。
The day breaks, for the birds are singing.注意：because不能与so连用②now(that)（既然，因为），considering that, seeing that（鉴于…的事实，考虑到…），in that（在于，由于）例：Now (that) dinner is ready, go and wash your hands.四，目的状语从句目的状语从句是表示行为目的的从句。
引导目的状语从句的主要连词有so that, in order that, in case, for fear that等。
①in order that与so that表示“为了，以便，”一般放在主句之后，in order that也可放在句首。
从句中常常使用一些情态动词，如can, could, may, might, should等。
例：I will speak slowly so that you can understand.注意：当主从句的主语一致时，so that和in order that引导的目的状语从句可以转换成相对应的动词不定式结构。
例：We got up early so that we would arrive in time.=We got up early so as to arrive in time.②in case, for fear that都表示“以免，以防，唯恐”，含有否定意义。
Better take more clothes in case the weather is cold.五，结果状语从句结果状语从句是表示事态结果的从句。
引导结果状语从句的连词有：so that, so…that, such…that等。
结果状语从句经常至于主句之后。
1.so that, such that。
其中so that最为常用，so或that常用于口语或非正式文体中；such that可以连用，意思是“如此…以至于”。
例：What has happened that you look so worried?2.so…that如此…以至于…。
其引导的结果状语从句有如下四种结构：①so+形容词/副词+that从句例：The village is so small that it cannot be shown in the map.②so+形容词+a/an+单数名词+that从句例：It was so hot a day that they all went swimming.③so+ many/few+复数名词+that从句例：I have had so many falls that I’m black and blue all over.④so+ much/little+不可数名词+that从句例：I had so little money then that I couldn’t even afford a used car.3.such…that如此…以至于…。
