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英语三大从句在英语中,主要有三大从句,即名词性从句包括主语从句,宾语从句,表语从句,同位语从句、形容词性从句即定语从句、副词性从句即状语从句,包括时间、条件、结果、目的、原因、让步、地点、方式等;定语从句一、关系代词引导的定语从句关系代词代替前面的先行词,并且在定语从句中充当句子成分,可以作主语、宾语、定语等;常见的关系代词有：who, that, which;它们的主格、宾格和所有格如下表所示：一关系代词who, whom和 whose的用法who代替人,是主格,在定语从句中作主语;An architect is a person who designs buildings. 建筑师是设计房屋的人;whom代替人,是宾格,在定语从句作宾语,在非正式英语常可省略;Do you know the gentleman whom we met in the school library yesterday 昨天我们在学校图书馆里遇到的那位先生你认识吗whose一般代替人,有时亦可代替物,是所有格,在定语从句作定语;The girl student whose father is a senior engineer used to study abroad. 其父是一位高级工程师的那个女学生过去在国外留学;Do you know the name of the hotel whose window we can see here 我们这儿能看到窗户的那个宾馆叫什么名字,你知道吗关系代词whose指代先行词hotel,正式用法应该用of which;whose window=the window of which,意思是：the window of the hotel;二关系代词which的用法which代替物,在定语从句作主语或宾语,作宾语时还可省略;I do not like stories which have unhappy endings.我不喜欢有不幸结局的小说;which可以换成that三关系代词that的用法that既可指人又可指物,在当代英语中大多指物,在定语从句作主语或宾语,作宾语时还可省略;： Is she the girl that sells newspapers她是卖报纸的那个女孩吗that可以换成whoWhere is the ice-cream that was in the fridge放在冰箱的冰激凌哪儿去了that可以换成whichIs this the book that you want to buy这是你要买的那本书吗 that可以换成which,在定语从句作宾语,还可以省略二、关系副词引导的定语从句常用的关系副词只有三个：when, where, why,在定语从句中充当时间、地点和原因状语;一关系副词when的用法关系副词when代替的先行词表示的是时间,when在定语从句作时间状语;In Beijing July and August are the months when it rains very often.北京的七月和八月是常下雨的月份;when先行词是months二关系副词where的用法关系副词where代替的先行词表示的是地点,where在定语从句作地点状语;During the Spring Festival I went back to the town where I was brought up.春节期间,我回到了生我养我的家乡;where的先行词是town三关系副词why的用法关系副词why代替的先行词表示的是原因,why在定语从句作原因状语;The reason why I am phoning you is to ask you whether you have got my email.我打电话给你的原因是想问问你是否收到了我的电子邮件;why先行词是reason, 当代英语里why可以用that替代,这时关系代词that就变成了表示原因的关系副词,还可以将why省略三、特殊关系代词as引导的定语从句一在固定搭配as…as, so…as, such…as, the same…as中,as引导定语从句You may take as many books as you want.你想要拿多少书就拿多少;第一个as是副词,修饰many的；第二个as才是关系代词,代替先行词books,在定语从句中作宾语二独立于主句之外,as引导定语从句As we know/ As is known to us, the earth turns around the sun. 正如我们所知,地球围绕太阳旋转;As we know和 As is known to us均为定语从句,as分别作宾语和主语,替代后面的主句;Taiwan is, as you know, an inseparable part of China.你知道,台湾是中国不可分割的一部分;关系代词as指代整个主句,在定语从句中作宾语;四、关系代词who, which与that的区别一关系代词who与that的区别1. 当关系代词用作主语时,多用主格who;He who loses hope loses all.失去希望的人就失去一切;先行词为代词he, they, any, all, one等时,多用whoI met Alice, who told me that she was learning Chinese.我遇见艾丽斯,她告诉我她在学汉语;在非限制性定语从句中,用who2. 当关系代词用作介词后的宾语时,用宾格whom,不用that;The man to whom our headmaster talked just now is our English teacher.我们校长刚才与他谈话的那个人是我们的英语老师;介词与关系代词紧密相连时,只能用宾格whom,不可用主格who注意：介词与关系代词不是紧密相连时,或者说介词放在句子后面时,这时可以用主格who,也可用that,还可以省略关系代词;因此,上面的这句话还可以有如下四种说法：1 The man whom our headmaster talked to just now is our English teacher.2 The man who our headmaster talked to just now is our English teacher.3 The man that our headmaster talked to just now is our English teacher.4 The man our headmaster talked to just now is our English teacher.3. 当关系代词泛指人时,多用that;He is a man that is never afraid of failure.他是个从不怕失败的人;that用来泛指人4. 当关系代词出现在who开头的疑问句时,应用that;例如：Who is the girl that is talking to Tom in English用英语同汤姆交谈的那个女孩是谁避免重复使用who,以免造成误解或语义含混不清二关系代词which与that的区别1. 当先行词为all, much, little以及不定代词anything, something, everything等时,关系代词多用that;All that glitters is not gold. 闪闪发光物,未必尽黄金;She told me everything that she knew. 她把她所知道的一切都告诉了我;2. 当先行词的前面有形容词最高级、序数词或限定词the only, the very, all, every, any, no 等时,关系代词一般都用that;This is the best novel that I have ever read. 这是我读过的最好的一部小说;He is the only person that has been invited to the ball. 他是惟一应邀参加舞会的人;3. 当关系代词出现在which开头的疑问句时,应用that;Which was the hotel that was recommended to the foreign guest 哪一个是推荐给外宾的宾馆这里使用that很明显是为了避免重复which4. 在非限制性定语从句中,关系代词一般只用which;Beijing, which is the capital of the People’s Republic of China, will host the 2008 Olympic Games. 北京是中华人民共和国的首都,将主办2008年奥运会;5. 介词后的关系代词用which,而不用that;She has collected 600 stamps, 60% of which are German stamps. 她收集了600张邮票,其中60％是德国邮票;五、定语从句的位置如前所述,定语从句一般总是直接置于所修饰的名词或代词之后;有时候,定语从句与先行词之间插入了其他的短语,这样它们被分隔了,这种情况下的定语从句被称作隔离定语从句;There was a girl upstairs who was shouting and crying, obviously mad.楼上有一个女孩,大喊大叫;很明显,她疯了;定语从句who was shouting and crying修饰the girl,被upstairs所隔开A new master will come tomorrow who will teach you German.明天要来一位新老师教你们德语了;定语从句置于句末以示强调名词性从句宾语从句一、引导词1由that 引导的陈述句性的宾语从句,在很多动词如say, think, wish , hope, see, believe, agree, expect, hear , feel等动词后;连词that只起连接作用,在从句中不做句子的成分,也无词汇意义,在口语中常被省略;如：I told him that he was wrong.在think, believe, suppose, expect等动词引起的宾语从句中,有时谓语尽管是否定意义,却不用否定形式,而将think 等动词变为否定形式;见语法：否定转移如：I don’t think you are right. 我认为你做的不对在许多带有复合宾语的句子中,that引导的宾语从句经常移到句子的后面,而用it做形式宾语;We think it wrong that he told a lie to everyone 我认为他向每一个人撒谎是错误的2 由连词if、 whether 引导的表示“是否…”的宾语从句;Whether, if 在从句中不做句子的成分,一般情况下,whether和if 可以替换;I don’t know if/whether he will come tomorrow.在介词后面的宾语从句中不用if引导Everything depends on whether we have enough money.宾语从句中有or not时不用if引导.I don’t know whether the movie star will come or not.和不定式连用作宾语时不用if引导Whether to go there or not hasn’t been decided.3由wh-引导的宾语从句;连接代词who, whom, whose, what, which和连接副词when, where, why, how 等连接的宾语从句,它们在句中即有连接从句的作用,又在句中充当句子的成分;Do you know which film they are talking about which做定语I don’t know where he lives. where 做地点状语二、宾语从句的语序,宾语从句的语序必须是陈述语序,既连接词+主语+谓语+其他成分 I believe that they will come soon.特例：有下列常见的问句,作为从句出现,是“不改变语句顺序”的;1. What's the matter2. What's wrong3. What's up4. What's the problem5. What's your trouble三、宾语从句的时态;宾语从句的时态受主句的限制,即：主句是一般现在时态,从句根据实际情况而定；主句是一般过去时态,从句用相应的过去的时态;如果从句的动作发生在主句之前,则从句要用过去完成时态;1 She says that she is a student.→ She said that she was a student.2She says that she will fly to Japan in a week. → She said that she would fly to Japan in a week.3She says that she has finished her homework alre ady. → She said that she had finished her homework already.1如果宾语从句说的是客观真理、自然现象或事实时,这时宾语从句要用一般现在时态;The teacher said that the earth goes round the sun.2Could you tell me…是用来征询对方的意见,语气委婉,并不表示过去;Could you tell me when we will visit the History Museum注意事项：3由陈述句变成宾语从句时,要注意人称的变化;She said: “I have been to England before.” → She said that she had been to England before. She asked me: “Do you like maths” → She asked me if I liked maths.4宾语从句与简单句的交换;由连接代词和连接副词引导的宾语从句,如果宾语从句的主语和主句的主语是同一个人时,可以用“疑问词+不定式”做宾语的简单句结构;I don’t know what I should do next. → I don’t know what to do next.DO SOME EXERCISES:you see AA. what he’s readingB. what is he readingC. what does he readD. he reads what2. Does Jack come from Japan Do you know合并成一个句子Do you know ___that__Jack __come___from Japandid your son say in the letter_He told me that he_D__ the Disney the next day.A. will visitB. has visitedC. is going to visitD. would visit4. He didn’t know___A____A. what’s the matterB. what the matter isC. what was the matterD. what the matter was5. Somebody called you just now, but I didn’t know__D__A. who were theyB. who they wereC. who was itD. who it was6. I want to know___D__A. what is his nameB. what’s his nameC. that his name isD. what his name is7. ---Could you tell me __C__she is looking for---Her cousin, Susan.A. thatB. whose C .who D. which8. ---What are you searching the Internet for---I’m trying to find out____.A. What is the difference between SARS and BIRDFLUB. How many persons have died in IraqC. How to protect our environmentD. Why is our Chinese team be able to beat Korea同位语从句一一般来说,在主从复合句中,用作同位语的从句叫同位语从句;它通常跟在某些名词之后,用以说明或解释该名词表示的具体内容;可以跟同位语从句的名词通常有：advice, decision, fact, hope, idea, information, message, news, promise, proposal, reply, report, suggestion, word消息,problem, question, doubt, thought等;eg: They were delighted at the news that their team had won.当听到他们队获胜的消息时,他们欣喜若狂;有时同位语从句可以不紧跟在被说明的名词后面,而被别的词隔开; 如：The thought came to him that Tom might have returned the book.他突然想起汤姆可能已经还了书了;二引导词1. The news that Mr. Li will be our new English teacher is true.2. He hasn’t made the decision whether he will go there.3. The question who should do the work is being discussed at the meeting.4. I have no idea what the boy is doing in the next room now.5. We haven’t yet settled the question where we are going to spend our summer vacation this year.6. I have no idea how I can get to the railway station.7. I have no idea when he will be back．小结：① that引导同位语从句时无词义,也不充当任何成分,但通常不可以省略,如句1；② whether引导同位语从句时意为“是否”,通常不能用if来代替, 如句2;③ 连接代词who, what等可以引导同位语从句,如句3, 4；④ 连接副词where, how, when等可以引导同位语从句, 如句5,6,7;三 that 引导的同位语从句和定语从句① 意义不同：同位语从句用来进一步说明前面名词的内容；而定语从句用来修饰、限定前面的先行词;试比较：1. The news that our team has won the final match is encouraging.2. The news that you told us is really encouraging.② that的功能不同：that引导同位语从句时是一个纯连词,不充当任何成分；而引导定语从句时,不仅起连接作用,而且还指代先行词并在从句中充当主语、宾语等成分;试比较：1. Dad made a promise that he would buy me a CD player if I passed the English test.2. Dad made a promise that excited all his children.③ 可否省略：that在引导同位语从句时,通常不可省略;在引导定语从句时,若在从句中作宾语,通常可以省略,若作主语则不可以省略;DO SOME EXERCISES:I. 请用适当的词填空,使下列句子意思完整;1. They expressed the hope _that_ they would come over to China soon.2. The fact ___that____ he didn’t see Tom this morning is true.3. Word has come __where_____ some American guests will come to our college for a visitnext week.4. He can’t answer the question ___how____ he got the money from his home yesterday.5. Do you have any idea __what___ is actually going on in the classroom6. The problem _______ we should have the meeting in the hall now must be decided at once. II. 下列各句中均有一处错误,请改正;1. Our team has won the game, that made us very happy.2. I’ve come with a message from Mr Wang how he won’t be able to see you this afternoon.3. He must answer the question if he agrees with what she said or not.4. I’ve read the book where you gave me the day before yester day.5. One of the men heldthe opinion when what the book said was right.表语从句表语从句只能置于主句之后,而主句的动词只能是连系动词;名词性从句在be等系动词后作表语时被称为表语从句The problem is how we can get the things we need.问题是我们怎样能弄到我们需要的东西;how 在表语从句中充当方式状语The scissors are not what I need. 这把剪刀不是我所需要的;what 在表语从句中充当宾语What I told him was that I would find him a good play. 我告诉他的是我会给他找个好剧本;what 在主语从句中作直接宾语, that作为表语从句的引导词在该表语从句中不充当句子成分, 不能省略That is what I want to tell you.那就是我想要对你讲的;what在表语从句中充当直接宾语That is why she failed to pass the exam. 那就是她考试不及格的原因;why 在表语从句中充当原因状语“That is why...”是常用句型, 意为“这就是……的原因/因此……”, 其中why引导的名词性从句在句中作表语, 该句型通常用于针对前面已经说明过的原因进行总结下面是两个与“That is why...”形式相似的结构, 它们与“That is why...”结构之间的关系要能够辨析清楚：1“That is why...”与“That is the reason why...”同义, 只不过从语法结构上讲, “That is the reason why...”中why引导的是—个定语从句, 将其中的the reason去掉则与“That is why...”结构一样 That is the reason why I cannot agree.2“That is because...”句型中从属连词because引导的名词性从句在此作表语, 这也是个常用句型, 意为“这就是为什么……/因为……”;“That is because...”与“That is why...”之间的不同在于“That is because...”指原因或理由, “That is why...”则指由于各种原因所造成的后果He did not see the film last night. That is because he had to help his little sister with her homework.昨天晚上他没有去看电影, 那是因为他得帮助他的妹妹做作业;第一句话说明结果, 第二句话说明原因He had seen the film before. That is why he did not see it last night.他以前曾看过那部电影, 因此他昨天晚上没有去看;第一句话说明原因, 第二句话说明结果考题1The traditional view is ____ we sleep because our brain is “programmed” to make us do so. 2007上海A. whenB. whyC. whetherD. that考题2You are saying that everyone should be equal, and this is ____ I disagree. 2004A. whyB. whereC. whatD. how考题3— I drove to Zhuhai for the air show last week.— Is that ____ you had a few days off 1999A. whyB. whenC. whatD. where考题4____ made the school proud was ____ more than 90% of the students had been admitted to key universities. 2003上海春A. What; becauseB. What; thatC. That; whatD. That; because考题5—Are you still thinking about yesterday’s game—Oh, that’s ____. 2003北京春A. what makes me feel excitedB. whatever I feel excited aboutC. how I feel about itD. when I feel excited表语从句与宾语从句的关系宾语从句和表语从句都属于名词性从句;其作用跟名词在句中的作用相同;故充当宾语的句子叫宾语从句,充当表语的句子叫表语从句;宾语从句1对于宾语从句要掌握以下三点①语序: 从句的语序必须是陈述句语序, 即“主语 + 谓语”这种形式;②时态: 当主句是一般现在时或一般将来时的时候, 从句可以是任何时态, 而当主句是一般过去时的时候, 从句时态必须是过去时范围的时态, 即一般过去时, 过去进行时, 过去完成时, 过去将来时;③连接词: 当从句意思完整, 主句意思肯定时, 连接词用that, 且可以省去当从句意思完整, 主句意思不确定或含否定含意时, 常用if或whether是否当从句意思不完整时, 连接词则是代替不完整部分的特殊疑问词;表语从句在句子中起表语作用的从句叫做表语从句,位于主句系动词的后面;表语从句的引导词和主语从句的引导词相同;也是名词性从句的一种;What the police want to know is when you entered the room.警察想知道的是你什么时候进的房间;The trouble is that we are short of funds困难是我们缺乏资金;This is what we should do这是我们应当做的;That is why I want you to work there那就是我要你在那儿工作的原因;His first question was whether Mr. Smith had arrived yet他的第一个问题是史密斯先生到了没有; 从句中的疑问句用正常语序,即陈述语序;as if, as though, because也可用来引导表语从句;She seems as if she had done a great thing她看起来好像做了一件大事;It is because you eat too much那是因为你吃得太多了;状语从句一状语从句的种类1.时间状语从句2.地点状语从句；3.原因状语从句；4.条件状语从句；5.目的状语从句；6.让步状语从句；7比较状语从句；8.程度状语从句；9.方式状语从句；10.结果状语从句;二状语从句的时态一般情况下,时间和条件状语从句的谓语动词一般用“一般现在时”表示“一般将来时”,用“现在完成时”表示“将来完成时”;1时间状语从句1.由when, while, as引导的时间状语从句;when, while和as的区别：when引导的从句的谓语动词可以是延续性的动词,又可以是瞬时动词;并且when有时表示“就在那时”;While引导的从句的谓语动作必须是延续性的,并强调主句和从句的动作同时发生或者相对应;并且while有时还可以表示对比;While my wife was reading the newspaper, I was watching TV.As表示“一边……一边”,as引导的动作是延续性的动作,一般用于主句和从句动作同时发生；as也可以强调“一先一后;As we was going out, it began to snow.当我们出门时,开始下雪了;as强调句中两个动作紧接着先后发生,而不强调开始下雪的特定时间2.由before和after引导的时间状语从句;before引导的从句不再用否定式的谓语,并且当before引导的从句位于主句之后,有时译成“就,才”; 时态：当主句用将来时,从句总是用现在时；如果before引导的从句谓语用的是过去时,则主句动词多用过去完成时,这样以便体现动作发生的先后;After表示主句动作发生在从句动作之后;主句和从句的动作的时间关系正好与before引导的从句相反;3.由till或until引导的时间状语从句;till和until一般情况下两者可以互换,但是在强调句型中多用until;并且要注意的是：如果主句中的谓语动词是瞬时动词时,必须用否定形式；如果主句中的谓语动词是延续性动词时,用肯定或否定形式都可以,但表达的意思不同;4.由since引导的时间状语从句;since引导的从句的谓语动词可以是延续性的动词,又可以是瞬时动词;一般情况下,从句谓语动词用一般过去时,而主句的谓语动词用现在完成时;但在It is ＋时间＋since从句的句型中,主句多用一般现在时;5.由as soon as, immediately, directly, instantly, the moment, the instant, the minute, 等引导的时间状语从句;这些连词都表示“一……就”;hardlyscarcely, rarely…when / before, no sooner…than相当于as soon as之意;主句用过去完成时,从句用一般过去时;当hardly, scarcely, rarely和no sooner位于句首时,主句应用倒装语序;6.由by the time引导的时间状语从句;时态的变化：在一般情况下,如果从句的谓语动词用一般过去时,主句的谓语动词用过去完成时；如果从句的谓语动词用一般现在时,主句的谓语动词用将来完成时;7.由each time, every time和whenever引导的时间状语从句;8.由as long as和so long as引导的时间状语从句;这两个连词表示“只要；和…一样长”;2地点状语从句地点状语从句一般由连接副词where, wherever等引导,已经形成了固定的句型,：句型1：Where＋地点从句,there＋主句;此句型通常译成“哪里……哪里就……”；主句在从句后面时,there可用可不用；如果主句在从句的前面时,一般都不用there;句型2：Anywhere/ wherever＋地点从句,＋主句;状语从句是句子的状语由一个从句充当,来修饰主句中的动词,形容词或副词等;状语从句都由从属连词引导,与主句连接,放在句末时,一般不在前面加逗号;3原因状语从句： because, since, as和for都表示原因;because语势最强,回答why提出的问题,用来说明人所不知的原因;当能够很明显的看出原因或人们已知原因,就用as或since;由because引导的从句如果放在句末,且前面有逗号,则可以用for来代替;但如果不是说明直接原因,而是多种情况加以推断,就只能用for;4目的状语从句：表示目的状语的从句可以由in order that, so that,等词引导;5结果状语从句：结果状语从句常由so...that 或 such...that引导,首先要了解so和such后面分别跟什么词;such是形容词,修饰名词或名词词组,so是副词,只能修饰形容词或副词;so 还可与表示数量的形容词many, few, much, little连用,形成固定搭配;The box is so heavy that I can't carry it.6让步状语从句：是由though, although 引导的状语从句;。
【科技英语的常用句型和翻译技巧】一、概述1. 翻译的要求The Criteria of Translation：信、雅、达2. 科技英语词汇（上节课已经介绍）3. 科技英语句子的特点二、科技英语常用句型及翻译1. 被动语态1）被动语态的常用原因常用被动语态主要见于以下几个方面：①不必或无法说出主动者For a long time aluminum has been thought as an effective material for preventing metal corrosion.长期以来，铝被当作一种有效的防止金属腐蚀的材料。
►The book has already been translated into many languages.②强调行为对象，而非行为者，将行为对象作为句子的主语Three machines can be controlled by a single operation.三台机器能由一个操作者操纵。
►The work must be finished at once.③为了更好的联系上下文►They are going to build a library here next year. It is going to be build beside the classroom building.2）被动语句的翻译方法（1）仍译为被动句最常见的是在谓语前加上助词“被”，也可使用“受到，遭到，得到，叫，称，让，给，加以，为……所”等句式。
偶尔也可不加任何词直接译出。
We remember how air can be made into a liquid. If the liquid is warmed again, it “boiled”and turns back into a gas.我们记得是如何把空气制成液体的。
如果给这种液体重新加热，它“沸腾汽化”，就又还原成气体。
英语同位语从句相关知识讲解英语语法中的从句有：名词性从句(主语从句、表语从句、宾语从句同位语从句)、形容词性从句(定语从句)、副词性从句(状语从句)。
英语从句的重点是，熟悉连接从句的连词、关系词的各种含义以及用法。
一、名词性从句英语语法中的名词性从句，在句子中起名词或者名词词组作用。
在英语复合句中充当主语、宾语、表语、同位语、介词宾语等。
因此，自然就有主语从句、宾语从句、表语从句和同位语从句。
1.同位语从句说明前一个名词具体内容的从句，一般位于被说明的名语之后，在含义上它与被说明的名词相等。
引导同位语从句的连词，最常见的是that，其次还有whether，what, which, who, when, where, why, how 等词。
1.由that引导The fact that everyone loves money is common sense.人人爱钱是常识。
注意：此句的the fact=that everyone loves money说明同位语从句的名词，只是表达语言、想法、事实等少数抽象名词，大多数句词不能也不需要接同位语从句，常见的有：idea想法thought想法question问题fact事实belief信念answer回答reply回复rumor谣言news消息order命令hope希望promise诺言suggestion建议doubt怀疑saying格言I like the idea that we hold an evening party.我喜欢开晚会这个想法。
Do you remember your promise that you treat us to hamburgers?你还记得你请我们吃汉堡包的承诺吗?The hope that every family owns a car will come true.每家有小车的希望会实现的。
注意：引导同位语从句的连词that通常不省略，但在非正式文体中也可以省去。
高中英语-定语从句、状语从句和同位语从句知识点总结复合句【语法要点】复合句是由一个主句加一个或几个从句所构成的句子。
从句只用作句子的一个成分，不能独立。
根据从句在句子中的作用，可分为名词性从句、定语从句和状语从句三类。
（一）名词性从句名词性从句包括主语从句、表语从句、宾语从句、同位语从句。
其关联词有连接词that、if、whether；疑问代词who、what、which和疑问副词when、where、how、why等。
1.名词性从句句法结构：从属连词that whether 主语从句That he will come is certain.（that不可省）Whether she is coming or not doesn’t matter too much.（不能用if）宾语从句I think（that）he will be all right in a few days.I went in and asked if（=whether）they had a cheap suit.I wonder whether（不能用if）it is true or not.表语从句The fact is（that）I have never been there.The question is whether（不能用if）it is worth doing.同位语从句The fact that she had not said anything surprised all of us.They asked me the question whether the work was worth doing.连接代词that who whom whose 主语从句Who will help him is not known.What he said is very important.Which side will win is not clear.宾语从句（1）作及物动词的宾语。
初中四大从句初中四大从句是指名词性从句、定语从句、状语从句和主语从句。
这四种从句在英语学习中非常重要，掌握它们的用法可以帮助我们更好地理解和运用英语语法。
下面，我将分别介绍这四种从句的用法和例句。
一、名词性从句名词性从句是指在句子中充当名词的从句，可以作主语、宾语、表语或同位语。
名词性从句通常由连词that, whether, if, who, whom, whose, what, which等引导。
1. 主语从句That he is a liar is beyond doubt.（他是个骗子是毫无疑问的。
）Whether he will come or not is still uncertain.（他是否会来还不确定。
）2. 宾语从句I don't know what he is doing now.（我不知道他现在在干什么。
） She asked me if I had finished my homework.（她问我是否完成了作业。
）3. 表语从句The problem is whether we should go or stay.（问题是我们是该走还是留。
）The fact is that he is always late.（事实是他总是迟到。
）4. 同位语从句The news that he won the prize surprised us all.（他获奖的消息让我们都很惊讶。
）The idea that we should work hard is very important.（我们应该努力工作的想法非常重要。
）二、定语从句定语从句是指修饰名词或代词的从句，通常由关系代词who, whom, whose, that, which等引导。
1. 修饰人的定语从句The girl who is singing is my sister.（唱歌的女孩是我妹妹。
）The teacher whom we met yesterday is very kind.（昨天我们遇到的老师非常友好。
三种易混从句的辨别专题策划：这样备考三类从句编者按：英语中有三类从句，即名词性从句、定语从句和状语从句。
这三类从句的学习、掌握和使用对同学们来说是一个颇为复杂的过程。
本专题通过对比分析这三大从句的区别，归纳三大从句与动词不定式的转换规律，希望能帮助同学们掌握区分从句与解答从句类考题的方法，并学会在书面表达中正确使用从句。
定语从句、同位语从句和状语从句有时候在形式上很相似，下面提供一些区分的方法。
一、定语从句与同位语从句定语从句与前面的名词是修饰与被修饰的关系，而同位语从句是用来说明前面名词的内容的。
that在定语从句中充当句子成分，可指物或人，而同位语从句中的that在从句中不充当任何句子成分，只起连接作用。
试比较：①The news（that/which）he told us was exciting.（定语从句，that/which在从句中作宾语，可以被省略）②The news that our team has won is exciting.（同位语从句，that从句是说明news的内容的，that在从句中不作任何成分，但不能省略）特别提醒：一般情况下，同位语从句紧跟在它所说明的名词之后，可是有时为了表达的需要，名词与从句之间被另外一些内容分隔开了，叫“分隔同位语从句”。
对于这类同位语从句，一定要根据句意，找准其所说明的名词。
例1 （2014年高考安徽卷）The exact year _____ Angela and her family spenttogether in China was 2008.A. whenB. whereC. whyD. which解析：本题中的定语从句的先行词是the exact year，后面的定语从句Angela and her family spent together in China中动词spent后面缺少宾语，所以使用关系代词which 引导这个定语从句，并在句中作宾语。
2022届高中英语新高考语法复习基础微专题名词性从句05快速区分同位语从句和定语从句同位语从句和定语从句一直以来都是困扰同学们的问题所在，那么怎么样才能快速区分同位语从句和定语从句呢？下面老师给大家带来一个快速区分这两种从句的小技巧。
同学们，我们先来看一下下面这两个句子：The boy that is eating ice-cream is my brother.The news that the company went bankrupt yesterday was false.那大家能不能来判断一下这两个句子，哪一个是定语从句？哪一个是同位语从句呢？首先我们来复习一下什么是：定语从句是由先行词引导的从句，在句法中做定语的功能。
我们可以理解成：定语从句起到形容词的作用，在句子中修饰从句前面的名词或者代词。
那么下面我们来看一个从句：The boy that is eating ice-cream is my brother.正在吃冰激凌的男孩是我的弟弟这里that做为关系词，引导了定语从句，整个从句做为定语修饰了前面的先行词“the boy”那么定语从句在这里可以拆分成两个句子：①the boy is my brother.男孩是我的弟弟②the boy is eating ice-cream.男孩正在吃冰激凌大家有没有发现，当定语从句被拆成两个句子的时候，他们都有一个共同的主语：the boy男孩从句中“正在吃冰激凌”，是对前面先行词“男孩”的修饰，我们可以理解成“正在吃冰激凌的男孩”我们再看下一个例句：The news that the company went bankrupt yesterday was false.这个公司昨天破产的消息是假的那么这个到底是定语从句还是同位语从句呢？我们继续来把它拆成两个句子：①the news was false消息是假的②the company went bankrupt yesterday.公司昨天破产我们来看，这两个句子有没有共同的主语呢？答案是没有。
学习中的常见同位语从句和定语从句同位语从句和定语从句在学习中的应用同位语从句和定语从句是英语学习中常见的句子结构，在写作和口语表达中起到了重要作用。
本文将详细介绍这两种从句的定义、用法和常见特点，以帮助学习者在使用这些句型时能够更加准确地表达自己的意思。
一、同位语从句的概念和用法同位语从句是一个被用来解释、说明或扩充主句中某个名词或代词的句子。
同位语从句通常用来引出一个定义、解释、观点、事实或判断等。
在句中，同位语从句通常紧跟在名词或代词之后，并用逗号与主句分开。
下面是一些常见的同位语从句的例子：1. He made a promise that he would come back soon.2. My hope is that we can achieve success together.3. We have no doubt that he will win the competition.同位语从句通常由引导词“that”引出，但并不是所有情况下都需要使用“that”。
有时候，同位语从句可以省略“that”而直接使用宾语从句。
同位语从句的一个重要特点是，它与名词的关系非常密切，对于理解主句的名词具有非常重要的作用。
二、定语从句的概念和用法定语从句是修饰名词或代词的从句，用来对名词进行进一步的解释或限定。
定语从句的主要作用是为名词提供更多的信息和背景知识。
以下是一些定语从句的例子：1. The house that he bought is very big.2. The person who is talking to the teacher is my friend.3. Do you know the reason why he left early?定语从句通常由关系代词（如that, who, whom, which, whose等）或关系副词（where, when, why）引导。
2015/12/2 Wednesday西安电子科技大学西安电子科技大学§5. 2 同位语从句1、一般情况 （1）公式§5. 2 同位语从句 The latter（后一）form has the advantage that it can be extended（扩展） to complex quantities .+ 某些抽象名词 +the this a/an O no形容词 物主代词that从句[“that”在从句中无词义、无 成分]③ “动宾译法”：这时该“抽象名词” 来自于可带有宾语从句的及物动词。
西安电子科技大学西安电子科技大学§5. 2 同位语从句（2）译法 ① “～ 这一 ……” 的§5. 2 同位语从句 During the past several years, there has been an increasing [a growing] recognition [realization; awareness] within business（商务）and academic（学术的） circles（界）that certain nations have evolved（发展）into information societies .The assumption that β = constant is often made to simplify analysis. R = r is the condition that power delivered（提供）by a given source is a maximum .西安电子科技大学西安电子科技大学§5. 2 同位语从句 Here we have used the definition （定义）that acceleration（加速度）is the rate（速率）of change of velocity .② 这一 ……：～ 以下的§5. 2 同位语从句 The main theoretical development in this decade（十年）has been in the recognition that material properties should be included in analytical models . This is equivalent to a statement that everything is attracted by the earth.This account for（解释）the observation（观察到的情况）that the resistivity of a metal increases with temperature .12015/12/2 Wednesday西安电子科技大学西安电子科技大学§5. 2 同位语从句§5. 2 同位语从句A consequence（结果）of the discovery of electricity was the observation that metals are good conductors while nonmetals are poor conductors .③ “there is every possibility that …” →“完全有可能……”There is every possibility that satisfactory results will be obtained.西安电子科技大学西安电子科技大学§5. 2 同位语从句（3）几个句型： ① “there is evidence that …”→ “有证据表明……”§5. 2 同位语从句2、由名词从句转变成的同位语从句（实 际上在从句前省去了“of;about;on;as to”） ★The question now arises whether this series（级数）converges（收敛）.There is evidence that Ohm’s law applies only to metallic conductors.The reader may have no idea what this symbol stands for.西安电子科技大学西安电子科技大学§5. 2 同位语从句§5. 2 同位语从句② “there is no doubt that …”→ “毫无疑问……”There is no doubt that mercury（水银） is a metal .The users have no guarantee（保证） how long this kind of device will be operating.22015/12/2 Wednesday西安电子科技大学西安电子科技大学§5. 3 名词从句1、一般情况 （1）引导词 ① 连接词：在从句中无成分§5. 3 名词从句（2）采用形式主语“it”的几个句型 ① “it is well known that …”→“众所 周知，……”that → （无词义） whether → “是否” if →“是否”（只能引导宾语从句时用）It is well known that Ohm’s law applies only to metallic conductors.② “it is clear [evident; apparent; obvious] that …” →“显然；很清楚……”西安电子科技大学西安电子科技大学§5. 3 名词从句② 连接代词：在从句中要作某一成 分。
科技文中常用的有： ★ what →“什么”、“……的 [内 容；方向；情况；话；……]”§5. 3 名词从句 It is clear that this equation has two roots（根）.③ “it follows that …”→ “（由此）得出 [到]……；因此……”which → “哪个 [本；枝；……]、哪些”From Ohm’s law it follows that the current is directly proportional to the applied voltage.西安电子科技大学西安电子科技大学§5. 3 名词从句③ 连接副词：在从句中一般作状语§5. 3 名词从句④ “it does not matter …”→ “……是 没有关系的”when → “何时；……的时间” where → “何地；……的地点” why → “为何；…….的理由” how → “如何；……的方式[原理]”It does not matter how the two numbers are added.⑤ “it makes no difference …”→ “……是没有区别的”It makes no difference where the radiation（辐射）comes from.32015/12/2 Wednesday西安电子科技大学西安电子科技大学§5. 3 名词从句（3）以介词开头的主语从句和宾语从句 （≠ 介词宾语从句 [它是介词后的一个完整 句子]）§5. 3 名词从句 It is necessary to find（求出）what that angle is.② “what” 是 一 个 复 合 关 系 代 词 （what = the thing[s] that）：译成“的 [话；情况；内容；东西；原因；方 向；……]”It does not basically make any difference in which direction an NPN transistor is operated（运用）.What I have said above is not necessarily correct.西安电子科技大学西安电子科技大学§5. 3 名词从句 You must determine for what values of x the following series（级数）is convergent（收敛的）.***The potential energy of a body depends upon where we choose the base height（基高）h = 0 to be.§5. 3 名词从句 What this book deals with is very useful. Its actual （ 实 际 的 ） direction is opposite to what has been assumed. Energy is what brings changes to materials. This is close to what has been observed.西安电子科技大学西安电子科技大学§5. 3 名词从句2、“what-从句”（主要在汉译时对 “what”这个词的处理问题） （1）普通情况 ① “what” 是一个疑问代词，译成： “什么；哪个[本；…]”或“多大[表示尺 寸、大小、数值]”§5. 3 名词从句 Gas takes the shape of what is holding （存放）it. What a battery does is to change chemical energy into electrical energy. The turning of the earth on its own axis is what makes the change from day to night .It is necessary to understand what inertia（惯性）is .42015/12/2 Wednesday西安电子科技大学西安电子科技大学§5. 3 名词从句 The particular mix（混合）of these frequencies is what determines the pitch （音调）of a person’s voice. The simplified assumptions do not correspond to what actually takes place in operation.§5. 3 名词从句（2）几个特殊句型的译法 ① “what is called + 补足语”→ 译 成“人们所说的[所称的；所谓的] + 补足 语” 注：“called”可用“named; termed; described as; known as; recognized as; referred to as; spoken of as等”来替代， 它们也可以是主动语态。
