2026届高三英语二轮复习之状语从句 导学案

高三二轮复习之状语从句 一．状语从句的定义：在复合句中由从句表示的状语称作状语从句，它可以用来修饰动词（包括非谓语动词）、定语或状语，或是整个句子。状语从句通常由一个连词引起，也可以由一个起连词作用的词组引起。 状语从句一般分为九大类 _______状语从句_______状语从句_______状语从句_______状语从句 _______状语从句 _______状语从句_______状语从句 比较状语从句 让步状语从句 He heard a knock at the door when he was doing his homework. Where there is a will, there is a way. He came late because he had to look after his sick mother. He got up early so that he could catch the early bus. He got up so early that he caught the early bus. You will be punished if you don’t work hard. You should do as your parents tell you to. He came earlier than I had expected. Although he failed the exam, he didn’t lose heart. 二．状语从句的分类： 1．时间状语从句： 在时间状语从句中，要注意时态一致，一般情况下主句是将来时的时候，从句要用_______________。引导时间状语从句的连词，根据意义和主从句之间的时间关系，可分类如下： （1）表示同时性，即主从句的谓语动作同时发生或几乎同时发生。 其连词有：when (当…的时候), while (当…的时候), as (当…的时候), as soon as (一…就…), the time (当…的时刻), the moment (当…的时刻), by the time (到…时候为止), next time (下次), the first time (第一次…的时候), the last time (上次…的时候)，immediately (一…就…), instantly (一…就…),directly (一…就…) 以下关联词引起的句子中， hardly /scarcely…when/before…（刚…就…）, no sooner…than…（刚…就…）前面常用_______________ (时态)，后面用_______________ (时态)。 1. Strike while the iron is hot.趁热打铁。 2. ____________________________(我洗地板的时候), you can be cleaning the windows. 3. ____________________________(我回家的时候), I met an old schoolmate of mine. 4. I’ll ring you up ____________________________(我一到家). 5. ____________________________(你一旦见过他), you will never forget him. 6. ________ had we got into the country ________ it began to rain. = We had hardly got into the country when it began to rain. 7. No sooner had he come home than she started complaining. = He had no sooner come home than she started complaining. 8. She rushed into the room immediately / the moment she heard the noise. 9. He made for the door ________________________________ (一听到敲门声). 10. He left me a good impression ________________________(我第一次见他时). （2）表示先时或后时，即主句的谓语动作发生在从句之前或之后。 主要连词有：after（在……之后），before（在……之前）, when(=after)等。如： 1. After / When the children had gone to bed, she began to prepare her lessons. 孩子睡觉了以后她开始备课。（从句的动作发生在主句的动作之前，所以从句用了过去完成时） 2. He had learned English for three years before he went to London. 他去伦敦之前已学了三年英语。（主句的动作发生在从句的动作之前，所以主句用了过去完成时） 常用句型： 要过很久才… ________________________________________________ 用不了多久就… ________________________________________________ 过了很久才… ________________________________________________ 不久就… ________________________________________________ It will be another five days ________________________________ (我们才能完成这个任务). _________________________ (没有过多久) I forgot it all. He ran off before I could stop him.（我还没来得及阻止他他就跑掉了。） It will still be two or three days _______ we finish our courses. The house fell down _______ he could run out. The holiday almost came to an end _______ I realized it. A. when B. before C. since D. after （3）表示习惯性、经常性，即从句描述的不是一次性动作，而是经常发生的习惯性动作。 主要连词有________ ________（每次）, each time（每次）, ____________（每当）等。 1. _________________________________(每当我们遇上困难的时候), they came to help us. 2. ______________________________(每次我见到她), she always wears a sweet smile. 3. Every time I went to his house, he was out.我每次去他家，他都出去了。 （4）表示持续性或瞬间性 主要连词有：since, ever since (自从), until (直到…才/为止),till (直到…才/为止) 常用句型: It is / has been + 段时间+since… 1. It is just a week since we arrived here. 我们到这儿刚刚一星期。 (主句的动作或状态持续时间较短，不能用ever since) 2. You have been reading to me ever since James went out. (ever 放在since之前是用来表示说话者强调主句动作或状态持续时间长) 3. My uncle went to Tibet in 1951. He has been living there ever since. It is three years since I smoked. ______________________________________ It is three years since I worked here. ________________________________________ It is three years since I knew him. _____________________________________ 4. Things went well until / till one night an accident happened.事情一切正常直到一天晚上发生意外 5. I knew nothing about it until / till he told me. 他告诉我了我才知道。 ★until与till及 not…until / till的用法 ①until和till都可表示“直到…为止”，用于_______(肯定 / 否定)句中，主句谓语动词为_________ (延续性 / 终止性) 动词。 He waited until / till we finished our meal.他一直等到我们吃完饭。 ②当until和till表示“直到…才…”时，用于_______(肯定 / 否定)句中，主句谓语动词为_________ (延续性 / 终止性) 动词。这时，until和till也可用before代替。 I didn’t leave until / till / before she came back.直到她回来，我才离开的。 ③until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。如： Until he told me, I knew nothing about it.他告诉我了我才知道。 ④当not until位于句首时，__________ (主句 / 从句) 中的主语、谓语要使用倒装语序： Not until she came back did I leave. = I didn’t leave until she came back. 直到你告诉我，我才意识到了我的错误。 ____________________________________________________________________________ ⑤在强调句型中一般用until，不用till。 It was not until she took off her dark glasses that I realized she was a famous film star. 2． 地点状语从句 地点状语从句是由__________（在…的地方）, ______________（无论哪里）引导的： 1. Wuhan lies where the Yangtze and the Han River meet.武汉位于长江和汉水汇合处。 2. Where there is a will, there is a way.有志者，事竟成。 3. You’d better make a mark __________________________________ (在你有问题的地方). 4. He would keep in touch with us _____________________________ (他无论在什么地方). 3． 原因状语从句 表示原因的状语从句可以由as (由于),because (因为), since (既然，由于), now that (既然), for (由于), in that等连词引导： 1. I do it because I like it.因为我喜欢我才干。(because不能与 so连用，为什么？) 2. He couldn’t have seen me, _______________________________ (因为我当时没在那儿).. 3.___________________________________ ( 既然大家都在), let’s try and reach a decision. 4. As she was ill, she didn’t come to the party.由于病了，她没来参加晚会。 ★because, as, for , since 的区别 类别 用法 例句 because because语气最强表示不知道的原因时用because,即说话人认为听话人不知道，因此because从句是全句最重要的部分，通常它被置于主句之后。下列情况下只能使用because: ①在回答why的问句时；②在用于强调句型时； ③被not所否定时。 You want to know why I’m leaving? I’m leaving because I’m full. for for的语气不及because, since, as强，引导的分句常放在主句之后，从句前通常用逗号，表示说话者为所做的推断和预测提供理由，或进行补充和解释。 It’s morning now, for the birds are singing. as/since 表示已经知道的原因时用as或since,即某种原因在说话人看来已经很明显，或已为听话人所熟悉，因此它是句中不很重要的部分。since要比as正式一些，它们通常被置于语句之前。Since 翻译为既然。 Since everyone is here, let’s start. 4． 目的状语从句 引导目的状语从句的主要连词有: __________ (以便), in order that (为了), for fear that (以防), 目的状语从句的谓语动词常与情态动词can, could, may, might, should连用 1). Let’s take the front seats so that we may see more clearly. 2). School was closed early in order that the children might go home ahead of the storm. 3). He took the name down for fear that he should forget it. 他把名字写下省得忘了。（该从句中一般用情态动词should+动词原形，或省略should） 5． 结果状语从句 引导结果状语从句的连词有：(so)that, so…that (如此…以致…), such…that (如此…以致…)等。 1). What has happened that you all look so excited? 2). We left in such a hurry that we forgot to lock the door. 3). The village is so small that it cannot be shown in the map. 4). Jenny is such a clever girl that all the teachers like her very much = Jenny is so clever a girl that all the teachers like her very much 注意：so + 形容词/副词 + that从句；such +名词 + that从句。 但是，当名词前有many, much, few, little (少)修饰时，要用so,不能用such。 1). He spoke ______ fast that I couldn’t catch up with him. 2). It is _____ fine weather that I decide to go for an outing. 3). He is ______ a clever boy that we all like him. 4). I have had ______ many falls that I am black and blue all over. 5). He has ______ few friends that he often feels lonely. 6). I had ______ little money then that I couldn’t afford a little present. 7). They are ______ little children that they didn’t know how to deal with it. 8). They received ______ little education that they didn’t know how to deal with it. 6． 条件状语从句 表示条件的状语从句可以由if (如果), once (一旦…), unless (除非), in case (万一), so /as long as (只要), as/ so far as (就…而言), on condition that (条件是…)。一般情况下当主句是将来时的时候，从句要用一般现在时。 1). _______________________ (只要我们不灰心), we’ll find a way to overcome the difficulty. 2). Send us a message ____________________________________ (万一你有什么困难). 3). If you leave at 6 o’clock tomorrow morning, you’d better get to bed now. 4). We’ll let you use the room _________________________________ (只要你能保持整洁). 5). ___________________________(据我所知), he is an expert on DNA. 6). He’ll accept the job unless the salary is too low/ if the salary is not too low. 他会接受这项工作的，除非薪水太少/如果薪水不太少的话。 7． 方式状语从句 方式状语从句常由as (与…一样), ____________ / ____________ (仿佛) 等词引导： 1. When in Rome, do as the Romans do.入乡随俗。 2. Leave things as they are.让一切顺其自然。 3. She stood at the door as if (=as though) she were waiting for someone. 4. He spoke as if he were the child’s father. 8． 比较状语从句 比较状语从句常由than (比) , as (与…一样) 等词引导： 1. It rains more often in Shanghai than (it does) in Beijing. 2. Our country is as big as the whole of Europe (is). 3. The result was not as/so good as I had expected. 常见句型：the +比较级+句子，the +比较级+句子 The busier he is, the happier he feels.他越忙越开心。 The sooner (it is), the better (it is). 9． 让步状语从句 让步状语从句由although (尽管), though (尽管), however (无论怎样), whatever (无论什么), whoever (无论谁), whomever (无论谁), whichever (无论哪个), whenever (无论何时), wherever (无论哪里), whether (是否), no matter (who, what, where, when) （无论…）, even if / though (即使) 等词引导。(while / as) 1. We won’t be discouraged even if(=even though) we fail ten times. 2. It was an exciting game, though / although no goals were scored. (though, although不能与 but连用，为什么？) 3. Whether you believe it or not, it’s true. 4. However (=No matter how) expensive it may be, I’ll take it. 5. While I admit there are problems, I don’t agree they can’t be settled. 6. Don’t let them in, _______________________________ . (不管他们是谁). 7. ________________________ (无论我说什么) or how I say it, he always thinks I’m wrong. 连词as也可以引导让步状语从句，但从句中要用特殊语序。 Young as he is, he knows a lot=Though he is young 或Young though he is, he…. ____________________________________(尽管他是个孩子), he is afraid of nothing. ____________________________________(尽管我们会失败), we won’t give up. ____________________________________(尽管她跑得慢), she got the first place. 一般情况下，unless相当于if…not，可以互换。如： I won’t let you in unless you show me your pass = I won’t let you in if you don’t show me your pass.如果你不出示通行证，我就不让你进来。 10．省略现象 有些表示时间、地点、条件、方式或让步等的状语从句中，如果谓语含有动词be，主语又和主句中的主语一致，或者主语是it，常把从句中的主语和谓语的一部分（特别是动词be）省略掉。注意状语从句中从句的省略现象 （1）连接词 + 过去分词 1. Don’t speak until spoken to.= Don’t speak until you are spoken to. 2. Pressure can be increased when needed.= Pressure can be increased when it is needed 3. Unless repaired, the washing machine is no use. =Unless it is repaired, the washing machine is no use. （2）连词 +　现在分词 Look out for cars when crossing the street(= when you are crossing …). （3）连词 + 形容词/其他 常见的有if necessary、if possible、when necessary、if any等。 1. She hurriedly left the room as though /if angry (= as though/if she was /were angry…).她急匆匆地走出屋去，好象很生气的样子。 2. _______ _________ (如果可能的话), I’d like to have two copies if it (= if it is possible,…). 3. _______ _________ (在必要的时候), I will help you. Exercises: 1. ________ the bell rang, all the students stopped writing immediately. 2. We were about to leave ________ it suddenly started to rain heavily. 3. ________ you have finished your homework, you can go out to play basketball. 4. She has made great progress ________ she entered Senior Three. 5. It won’t be long ________ we know the results of the college entrance exam. 6. He had scarcely arrived at the airport ________ the plane took off. 7. ________ you had come earlier, you would have met the famous professor. 8. I won’t attend the party ________ I am specially invited by the host. 9. You will fail the exam ________ you review your lessons carefully. 10. ________ rich he may become, he will never forget his humble origins. 11. ________ you say, I will never believe your words again. 12. ________ you go, you should always keep your mother’s words in mind. 13. He didn’t come to school yesterday ________ he was seriously ill in bed. 14. We all like the new teacher ________ he always makes his classes lively. 15. It was do cold a day ________ we didn’t want to go outdoors. 16. He spoke so fast ________ most of us couldn’t follow what he said. 17. Do ________ the teacher told you, or you will make serious mistakes. 18. Leave the room ________ it was when you entered it this morning. 19. ________ there is a will, there is always a way to solve problems. 20. I was walking along the street ________ I came across an old friend. 参考答案 一．状语从句的定义：在复合句中由从句表示的状语称作状语从句，它可以用来修饰动词（包括非谓语动词）、定语或状语，或是整个句子。状语从句通常由一个连词引起，也可以由一个起连词作用的词组引起。 状语从句一般分为九大类 时间状语从句 地点状语从句 原因状语从句 目的状语从句 结果状语从句 条件状语从句 方式状语从句 比较状语从句 让步状语从句 He heard a knock at the door when he was doing his homework. Where there is a will, there is a way. He came late because he had to look after his sick mother. He got up early so that he could catch the early bus. He got up so early that he caught the early bus. You will be punished if you don’t work hard. You should do as your parents tell you to. He came earlier than I had expected. Although he failed the exam, he didn’t lose heart. 二．状语从句的分类： 1．时间状语从句： 在时间状语从句中，要注意时态一致，一般情况下主句是将来时的时候，从句要用一般现在表示将来。引导时间状语从句的连词，根据意义和主从句之间的时间关系，可分类如下： （1）表示同时性，即主从句的谓语动作同时发生或几乎同时发生。 其连词有：when (当…的时候), while (当…的时候), as (当…的时候), as soon as (一…就…), the time (当…的时刻), the moment (当…的时刻), by the time (到…时候为止), next time (下次), the first time (第一次…的时候), the last time (上次…的时候)，immediately (一…就…), instantly (一…就…),directly (一…就…) 以下关联词引起的句子中， hardly /scarcely…when/before…（刚…就…）, no sooner…than…（刚…就…）前面常用过去完成时态 (时态)，后面用一般过去时态 (时态)。 1. Strike while the iron is hot.趁热打铁。 2. While I am cleaning the floor(我洗地板的时候), you can be cleaning the windows. 3. When I returned home(我回家的时候), I met an old schoolmate of mine. 4. I’ll ring you up as soon as I get home(我一到家). 5. Once you see him(你一旦见过他), you will never forget him. 6. Hardly / Scarcely had we got into the country when it began to rain. = We had hardly / scarcely got into the country when it began to rain. 7. No sooner had he come home than she started complaining. = He had no sooner come home than she started complaining. 8. She rushed into the room immediately / the moment she heard the noise. 9. He made for the door as soon as he heard the knock at the door (一听到敲门声). 10. He left me a good impression the first time I saw him (我第一次见他时). （2）表示先时或后时，即主句的谓语动作发生在从句之前或之后。 主要连词有：after（在……之后），before（在……之前）, when(=after)等。如： 1. After / When the children had gone to bed, she began to prepare her lessons. 孩子睡觉了以后她开始备课。（从句的动作发生在主句的动作之前，所以从句用了过去完成时） 2. He had learned English for three years before he went to London. 他去伦敦之前已学了三年英语。（主句的动作发生在从句的动作之前，所以主句用了过去完成时） 常用句型： 要过很久才… It will be long before... 用不了多久就… It won’t be long before... 过了很久才… It was long before... 不久就… It wasn’t long before... It will be another five days before we finish the task (我们才能完成这个任务). It wasn’t long before (没有过多久) I forgot it all. He ran off before I could stop him.（我还没来得及阻止他他就跑掉了。） It will still be two or three days before we finish our courses. The house fell down before he could run out. The holiday almost came to an end _______ I realized it. A. when B. before C. since D. after （3）表示习惯性、经常性，即从句描述的不是一次性动作，而是经常发生的习惯性动作。 主要连词有every time（每次）, each time（每次）, whenever（每当）等。 1. Whenever we met with difficulties (每当我们遇上困难的时候), they came to help us. 2. Every / Each time I see her (每次我见到她), she always wears a sweet smile. 3. Every time I went to his house, he was out.我每次去他家，他都出去了。 （4）表示持续性或瞬间性 主要连词有：since, ever since (自从), until (直到…才/为止),till (直到…才/为止) 常用句型: It is / has been + 段时间+since… 1. It is just a week since we arrived here. 我们到这儿刚刚一星期。 (主句的动作或状态持续时间较短，不能用ever since) 2. You have been reading to me ever since James went out. (ever 放在since之前是用来表示说话者强调主句动作或状态持续时间长) 3. My uncle went to Tibet in 1951. He has been living there ever since. It is three years since I smoked. 我戒烟三年了。 It is three years since I worked here. 我不在这儿工作已经三年了。 It is three years since I knew him. 我认识他三年了。 4. Things went well until / till one night an accident happened.事情一切正常直到一天晚上发生意外 5. I knew nothing about it until / till he told me. 他告诉我了我才知道。 ★until与till及 not…until / till的用法 ①until和till都可表示“直到…为止”，用于_______(肯定 / 否定)句中，主句谓语动词为_________ (延续性 / 终止性) 动词。 He waited until / till we finished our meal.他一直等到我们吃完饭。 ②当until和till表示“直到…才…”时，用于_______(肯定 / 否定)句中，主句谓语动词为_________ (延续性 / 终止性) 动词。这时，until和till也可用before代替。 I didn’t leave until / till / before she came back.直到她回来，我才离开的。 ③until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。如： Until he told me, I knew nothing about it.他告诉我了我才知道。 ④当not until位于句首时，__________ (主句 / 从句) 中的主语、谓语要使用倒装语序： Not until she came back did I leave. = I didn’t leave until she came back. 直到你告诉我，我才意识到了我的错误。 Not until you told me did I realize my mistake. ⑤在强调句型中一般用until，不用till。 It was not until she took off her dark glasses that I realized she was a famous film star. 2． 地点状语从句 地点状语从句是由where（在…的地方）, wherever（无论哪里）引导的： 1. Wuhan lies where the Yangtze and the Han River meet.武汉位于长江和汉水汇合处。 2. Where there is a will, there is a way.有志者，事竟成。 3. You’d better make a mark where you have questions (在你有问题的地方). 4. He would keep in touch with us wherever he was (他无论在什么地方). 3． 原因状语从句 表示原因的状语从句可以由as (由于), because (因为), since (既然，由于), now that (既然), for (由于), in that等连词引导： 1. I do it because I like it.因为我喜欢我才干。(because不能与 so连用，为什么？) 2. He couldn’t have seen me, for I wasn’t there at the moment (因为我当时没在那儿). 3.Since everyone is present ( 既然大家都在), let’s try and reach a decision. 4. As she was ill, she didn’t come to the party.由于病了，她没来参加晚会。 ★because, as, for , since 的区别 类别 用法 例句 because because语气最强表示不知道的原因时用because,即说话人认为听话人不知道，因此because从句是全句最重要的部分，通常它被置于主句之后。下列情况下只能使用because: ①在回答why的问句时；②在用于强调句型时； ③被not所否定时。 You want to know why I’m leaving? I’m leaving because I’m full. for for的语气不及because, since, as强，引导的分句常放在主句之后，从句前通常用逗号，表示说话者为所做的推断和预测提供理由，或进行补充和解释。 It’s morning now, for the birds are singing. as/since 表示已经知道的原因时用as或since,即某种原因在说话人看来已经很明显，或已为听话人所熟悉，因此它是句中不很重要的部分。since要比as正式一些，它们通常被置于语句之前。Since 翻译为既然。 Since everyone is here, let’s start. 4． 目的状语从句 引导目的状语从句的主要连词有: so that (以便), in order that (为了), for fear that (以防), 目的状语从句的谓语动词常与情态动词can, could, may, might, should连用 1). Let’s take the front seats so that we may see more clearly. 2). School was closed early in order that the children might go home ahead of the storm. 3). He took the name down for fear that he should forget it. 他把名字写下省得忘了。（该从句中一般用情态动词should+动词原形，或省略should） 5． 结果状语从句 引导结果状语从句的连词有：(so)that, so…that (如此…以致…), such…that (如此…以致…)等。 1). What has happened that you all look so excited? 2). We left in such a hurry that we forgot to lock the door. 3). The village is so small that it cannot be shown in the map. 4). Jenny is such a clever girl that all the teachers like her very much = Jenny is so clever a girl that all the teachers like her very much 注意：so + 形容词/副词 + that从句；such +名词 + that从句。 但是，当名词前有many, much, few, little (少)修饰时，要用so,不能用such。 1). He spoke so fast that I couldn’t catch up with him. 2). It is such fine weather that I decide to go for an outing. 3). He is such a clever boy that we all like him. 4). I have had so many falls that I am black and blue all over. 5). He has so few friends that he often feels lonely. 6). I had so little money then that I couldn’t afford a little present. 7). They are such little children that they didn’t know how to deal with it. 8). They received so little education that they didn’t know how to deal with it. 6． 条件状语从句 表示条件的状语从句可以由if (如果), once (一旦…), unless (除非), in case (万一), so /as long as (只要), as/ so far as (就…而言), on condition that (条件是…)。一般情况下当主句是将来时的时候，从句要用一般现在时。 1). So / As long as we don’t lose heart (只要我们不灰心), we’ll find a way to overcome the difficulty. 2). Send us a message once you have any difficulty (万一你有什么困难). 3). If you leave at 6 o’clock tomorrow morning, you’d better get to bed now. 4). We’ll let you use the room on condition that you keep it tidy (只要你能保持整洁). 5). As / So far as I am concerned (据我所知), he is an expert on DNA. 6). He’ll accept the job unless the salary is too low/ if the salary is not too low. 他会接受这项工作的，除非薪水太少/如果薪水不太少的话。 7． 方式状语从句 方式状语从句常由as (与…一样), as if / as though (仿佛) 等词引导： 1. When in Rome, do as the Romans do.入乡随俗。 2. Leave things as they are.让一切顺其自然。 3. She stood at the door as if (=as though) she were waiting for someone. 4. He spoke as if he were the child’s father. 8． 比较状语从句 比较状语从句常由than (比) , as (与…一样) 等词引导： 1. It rains more often in Shanghai than (it does) in Beijing. 2. Our country is as big as the whole of Europe (is). 3. The result was not as/so good as I had expected. 常见句型：the +比较级+句子，the +比较级+句子 The busier he is, the happier he feels.他越忙越开心。 The sooner (it is), the better (it is). 9． 让步状语从句 让步状语从句由although (尽管), though (尽管), however (无论怎样), whatever (无论什么), whoever (无论谁), whomever (无论谁), whichever (无论哪个), whenever (无论何时), wherever (无论哪里), whether (是否), no matter (who, what, where, when) （无论…）, even if / though (即使) 等词引导。(while / as) 1. We won’t be discouraged even if(=even though) we fail ten times. 2. It was an exciting game, though / although no goals were scored. (though, although不能与 but连用，为什么？) 3. Whether you believe it or not, it’s true. 4. However (=No matter how) expensive it may be, I’ll take it. 5. While I admit there are problems, I don’t agree they can’t be settled. 6. Don’t let them in, whoever they are . (不管他们是谁). 7. Whatever I say (无论我说什么) or how I say it, he always thinks I’m wrong. 连词as也可以引导让步状语从句，但从句中要用特殊语序。 Young as he is, he knows a lot=Though he is young 或Young though he is, he…. Child as / though he is (尽管他是个孩子), he is afraid of nothing. Fail as we may (尽管我们会失败), we won’t give up. Slowly as she ran (尽管她跑得慢), she got the first place. 一般情况下，unless相当于if…not，可以互换。如： I won’t let you in unless you show me your pass = I won’t let you in if you don’t show me your pass.如果你不出示通行证，我就不让你进来。 10．省略现象 有些表示时间、地点、条件、方式或让步等的状语从句中，如果谓语含有动词be，主语又和主句中的主语一致，或者主语是it，常把从句中的主语和谓语的一部分（特别是动词be）省略掉。注意状语从句中从句的省略现象 （1）连接词 + 过去分词 1. Don’t speak until spoken to.= Don’t speak until you are spoken to. 2. Pressure can be increased when needed.= Pressure can be increased when it is needed 3. Unless repaired, the washing machine is no use. =Unless it is repaired, the washing machine is no use. （2）连词 +　现在分词 Look out for cars when crossing the street(= when you are crossing …). （3）连词 + 形容词/其他 常见的有if necessary、if possible、when necessary、if any等。 1. She hurriedly left the room as though /if angry (= as though/if she was /were angry…).她急匆匆地走出屋去，好象很生气的样子。 2. If possible (如果可能的话), I’d like to have two copies if it (= if it is possible,…). 3. When necessary (在必要的时候), I will help you. Exercises: 1. When/As 2. when 3. Once 4. since 5. before 6. when 7. if 8. Unless 9. unless 10. However 11. Whatever 12. wherever 13. because/as/since 14. because/as 15. that 16. that 17. as 18. as 19. where 20. when 11 学科网（北京）股份有限公司 $