ClausesLynn Long从句是什么，主句是什么当我们在表达时.有时句子中的某个成分需要用另一条句子来表达。这种情况下.整个 句子就叫主句，而表达主句中某个成分的句子就是从句。例如，定语从句用于充当定语。按 照从句所代表的句子成分的不同，可以把从句分为6种：定语从句，状语从句，宾语从句， 主语从句，同位语从句和表语从句。其中，因为宾语从句、主语从句和同位语从句代表的 是主句中的名词性成分，所以这三种从句又统称为名词性从句。（表语从句在结构上也与名 词性从句相似，所以也可以归入名词性从句。）虽然从句一般都包含句子的要素如主语和谓语.但从句不能独立成句，只能充当主句中 的某个成分。从句前面一般由引导词如that, who, whom, which, when, why, how, whether 等作引导。举例：定语从句【跟在名词或代词后边儿】 The letter gave them all the information that they needed. 这封信给他们提供了所需要的一切信息。 The advice that we have got was of no avail.我们得到的建议完全没用。 The one who drives a car is my younger brother. 开汽车的那个人是我的弟弟。状语从句 If you pull too hard you will break the rope. 如果你太用力拉，就会把绳子拉断。 He was thrown into unemployment when the factory closed. 他在工厂倒闭后被迫失业了。宾语从句【跟在实义动词后边儿】 Can you estimate how long it will take to go to the station? 你能估计一下去车站要多久吗？ He can not decide when to leave.他没法决定什么时候动身。 主语从句【搁在实义动词前边儿】 What you say does not accord with the previous evidence. 你所说的与以前的证词不一致。 That mathematics is the base of other science is known to all of us. 众所周知数学是其他科学的基础。表语从句【跟在系动词后边儿】 The reason Im here is because I need to get my bill. 我在这儿的原因是我需要拿到账单。 My suggestion is that you should adapt yourself to the new job as soon as possible. 我的建议是你要尽快适应新的工作。同位语从句【跟在含有内容的名词后边儿】 Tears filled her eyes at the thought that she might never see him again. 一想到她再也见不到他，她满眼是泪。 They have no ideas what they should do next. 他们不知道接下来该做什么。Attributive Clause定语从句【跟在名词或代词后边儿】定语从句是形容词性从句，用来修饰主句中的名词或代词。其作用相当于定语，故称 定语从句。被定语从句所修饰的对象称为先行词。定语从句一般紧随它所修饰的先行词之 后，并由关系代词或关系副词引导。The letter gave them all the informationthatthey needed.（先行词）（关系代词）Dylan went back to the village where he was born.（先行词）（关系副词）关系代词：that、which、who、whom、whose、as 关系副词：when、where、why根据定语从句与先行词之间的关系紧密程度，可以将定语从句分为限制性定语从句和 非限制性定语从句。一、限制性定语从句限制性定语从句用来修饰和限制先行词，与先行词之间的关系非常密切，它所修饰的 先行词代表一个、一些或一类特指的人或物，说明先行词的性质、身份、特征等状况。如 果去掉限制性定语从句，原句意思会含糊不清。先行词在限制性定语从句中充当某个语法 成份（如充当主语、宾语，定语或状语等）。限制性定语从句的关系代词：that、which、who、whom、whose、as；关系副词：when、 where、why、how1、由关系代词引导的限制性定语从句由that引导的定语从句that可以指人或物。在定语从句中作主语、宾语或表语，作宾语或表语时可以省略。 The man that visited our school is from Australia 到访我们学校的那个人来自澳大利亚。 Is oxygen the only gas that helps fire burn?氧气是唯一的助燃气体吗？ The girl （that） I saw is called Mary.我见到的那个女孩名叫玛丽。 Is there anything else （that） you require?你还需要别的东西吗？ My hometown is no longer the place (that) it used to be. 我的家乡再也不是以前那个样子了。由which引导的定语从句which指物，在定语从句中作主语或宾语。 I do not like stories which have unhappy endings. 我不喜欢有不幸结局的小说。 That was a fault which could not be forgiven. 那是不能饶恕的错误。 Have you seen the watch (which) I left here just now? 你看到我刚才放在这里的手表了吗？ These are the wires with which different machines are connected. 这些是连接不同机器的电线。 The reason for which he refused to go to the party was that they had not invitedhim to.他拒绝去赴宴的原因是他没受到他们的邀请。由who引导的定语从句who指人，在定语从句中作主语。 Anybody who breaks the laws will be punished.任何违反法律的人都将受到惩 罚。 Do you know the boys who are standing over there?你认识站在那边的那些男 孩吗？由whom引导的定语从句whom指人，在定语从句中作宾语或表语。 The doctor whom you are waiting for has left. 你一直在等的那位医生已经离开了。 Is she the very person whom we must take good care of? 她就是那个我们必须好好照顾的人吗？ They are looking for the patient on whom doc tors jus t performed an opera tion. 他们正在寻找那位医生刚刚给他做过手术的病人。注在口语中，可以用who代替whom,在定语从句中作宾语。 The man who I saw told me to wait. 我见到的那个人叫我等。 I know the man who you were speaking to just now. 我认识你刚刚和他讲话的那个人。由whose引导的定语从句whose通常指人，也可指物，在定语从句中作定语。 There are some students whose questions I cant answer. 有些学生的问题我回答不了。 They lived in a room whose window opened to the south. 他们住在一间窗户朝南开的房间里。 Once there was a wise king whose name was Alfred. 从前有一个明智的叫阿尔弗雷德的英国国王。 Can you see the mountain whose top is covered with snow?你看得见山顶上覆盖着雪的那座山吗？2、由关系副词引导的限制性定语从句由when引导的定语从句 |丨丨 never forget the days when I worked with you. 我永远不会忘记我与你共事的日子。 Can you still remember that evening when we met for the first time? 你还记得我们第一次见面的那个晚上吗？由where引导的定语从句 This is the town where I was born. 这是我出生的城市。 She would like to live in a country where it never snows. 她喜欢住在不下雪的国家。 Who can think of a situation where this phrase can be used? 谁能想出用这个短语的情况？ Her career has reached the stage where she must decide what to do next. 她的事业已经到了必须决定下一步该怎么办的阶段。 I ve come to the point where I cant stand him. 我已经到了无法忍受他的地步。由why引导的定语从句 I dont know the reason why he didnt tell it to his father. 我不明白为什么他没有把这件事告诉他父亲。 Thats the reason why she left home. 那就是她离家出走的原因。 Is this the reason why he refused our offer? 这就是他拒绝我们帮助他的理由吗？ We cant accept the excuse why you were absent. 我们无法接受你缺席的借口。 This is the explanation why they put off the meeting. 这是他们为何推迟会议的解释。3、有一些定语从句常可省略引导词 一些表示时间的定语从句可以省略when。 You may go there any time you like. 你随便什么时候都可以去那儿。 By the time you arrive in London, we will have stayed there for two weeks. 等你到达伦敦的时候我们已经在那里呆了两周了。 I still remember the first time I met her.