复合句：名词性从句 定语从句 状语从句
复合句是由一个主句加一个或几个从句构成的句子。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、形容词性从句（定语从句）和副词性从句（状语从句）三类。
（一）名词性从句
复合句中起名词作用的从句叫名词性从句。名词性从句可分为主语从句、表语从句、同位语从句和宾语从句。其关联词有:连接词that，whether;连接代， what, whatever, which, whichever, who, whom, whose，whoever, whomever;连接副词 when, where, how, why 等。
1. 主语从句及形式主语
在句子中充当主语的从句称为主语从句，位于句首主语的位置。当主语从句位于句首时，引导从句的连接词一律不能省略，其谓语动词通常用早篸。引导主 语从句的连接词分以下三种：
1) that, whether引导主语从句，只起连接作用，在句中不充当成分。连接词that在句子中没有词义，但不能省略。
that, whether引导的主语从句 谓语及其他 That we are losing high-level scientists astonishes us. That she won the game made a tremendous stir in our country Whether one can succeed dependson how hard he works. Whether it will do us harm or good remains to be seen. Just because he is over sixty doesn’t mean he must retire. 说明：在传统英语中,because是不能引导主语从句的，但在非正式文体中，特别在现代英语中，已很常见。但仅用于“Just because +句子+ doesn’t mean +句子”句型中。从句只能位于句首，且不能用it作形式主语。又如： Just because it has a good tune doesn’t mean it is great music.
2) 连接代词 what, whatever, which, whichever, who, whom, whose, whoever, whomever等引导主语从句，有其本身的词义，在从句中充当主语或宾语，有些可作表语或定语，因此不能省略。这些具有疑问含义的连接代词引导的从句必须用陈述句形式，不能倒装。
连接代词引导的主语从句 谓语及其他 What we need is more time. Whatever is worth doing is worth doing well. Which team will win the match is still unknown, Whichever of you comes in first will receive a prize. Who has never tasted what is bitter does not know what is sweet. . Whom we must serve is a question of vital importance. 至关重要 Whose fault it is is quite clear now. Whoever takes interest in the paper can ask for a copy. Whoever/whomever you invite will be welcome. 说明：that引导名词性从句与what引导名词性从句的比较。 ? that引导名词性从句，在句中不充当成分，that没有词义，但不能省略： That we must combine theory with practice is an important principle. That mathematics is the base of other science is known to all of us. ? what引导名词性从句，可在句中充当成分。有以下两种类型： a) 关系代词型:what = the thing(s) that，意为“所?的事/物”，表示已知信息： What is happening now happened before.现在正在发生的事情此前也发生过。 What we are doing today was not possible in the old days. b) 疑问代词型：意为“什么；什么样的”，引导疑问从句，表示未知信息： What she did after that was not clear to us. What will happen is left up to the viewer’s imagination. What motive he could have is not quite clear.
3）连接副词when，where, how, why等引导主语从句，连接副词本身在从句中作状语。它们引导的从句必须用陈述句形式，不能倒装。 连接副词引导的主语从句 When she will be back Where she has gone How the computer was invented Why he did it 谓语及其他 depends on the weather. is a mystery. is a long story. remains a puzzle for ever.
4）形式主语it的正确使用。
从句作主语常给人头重脚轻的感觉，因此，人们常用it作形式主语，把主语从句放在句末。用it作形式主语的句子主要有以下几种： ①It+ be＋形容词＋主语从句
It is strange that he knows nothing about it It is uncertain whether he will come or not 常见的形容词还有: apparent, clear, evident, obvious, advisable, preferable, reasonable, essential, necessary, probable, true, strange, amazing, natural 等 ②It +be＋名词词+主语从句 It is a fact that many people are scared to fly. It is still a question whether we shall have our sports meet. 常见的形容词还有: a fact, a general rule , a good thing, a mystery， a pleasure,a question , a pity , a shame , a truth，a wonder，a matter of common knowledge等 ? It+ be +过去分词+主语从句 It is predicted that in 10 years or so the roof will probably collapse. It is still unknown which team will win the match. 常见的过去分词还有： accepted, announced , arranged , assumed , considered , decided, declared,estimated，expected，generally agreed, well-known, pointed out等 ④ It+不及物动词+主语从句
It happened that I wasn't there that day. It doesn’t matter what other people think of me. 常见的不及物动词还有： chance（正好）, seem, appear, turn out （结果）, goes without saying（不言而喻） , occur to sh. （某人想到） , stand to reason （合乎情理） ⑤It＋动词＋宾语＋主语从句 It makes no difference whether you go or stay. It makes no difference where we shall have the meeting 此结构仅用于： “ It makes no difference ＋主语从句” ； “ It doesn't make any/much difference＋主语从句” 的据句型中，意为“ 无差别” ，“ 无关系” ， “ 无影响”。 ⑥It +be ＋ 介词短语＋ 主语从句
It is of great importance whether we can improve our research. It isl goes without saying that health is above wealth
1. 表语从句
在句子中位于系动词之后充当表语的从句称为表语从句，由连接词that, whether, as, as if;连接代词who, whose, what, which;连接副词 when, where, how, why等引导。 1) 由 that, whether, as, as if 引导表语从句。 主语+系动词 表语从句 Chances are that man will eventually land on Mars. The reason why he was late was that he missed the early bus this morning. , What he wants to know is whether he should start now. The village people are not as they used to be. It looks as if it’s going to rain. The meat tastes as if it has already gone bad. 说明:①that引导表语从句本身没有词义，在从句中不充当成分，主句的系动词通常是be。口语中连接词that可以省略，书面语中最好不省略。 ②whether, as引导表语从句，主句系动词常为be，不能用if代替whether。 ③as if引导表语从句，主句系动词常为look, feel, seem, taste等。 ④当主语是表示建议、命令、愿望等的词语时，that引导的表语从句要用虚拟语气。 2) 由who, whose, what, which引导表语从句在从句中充当成分。 主语+系动词 表语从句 The questions is who can complete the difficult task. What I want to know is whose mobile phone is stolen. Things are not what they seem. The problem is which experiment we should do first. 3) 由when, where, how, why引导表语从句在从句中充当状语。 主语+系动词 表语从句 What I want to know is when she’ll be back. Probably this is where the accident happened. This is how she carries on her work all the year round. That is why we put the meeting off. 4）用because引导的表语从句仅限于以下一个句型，用于表示原因。其结构是:This/That/It is because + 从句… It is/That is because引导表语从句 I think it’s because you are eating too much.我想是因为你吃得太多。 Tom was late for work this morning. That is because he overslept.汤姆今天早晨上班迟到了。那是因为他睡过头了。 5）主语是reason,表语从句用that引导，不用why或because0 The reason (/) something happens is that +从句
The reason why/that something happens is that +从句 The reason (/;why;that) is that引导表语从句 The reason I’m phoning you is that I want to invite you to a party. One reason why Hamlet is such a successful play is that it appeals to many different people. 2. 同位语从句
1）同位语的概念
两个成分处于相同地位，起修饰作用的成分叫同位语（appositive）。同位语是一种后置修饰语，对与之同位的名词（本位语）提供补充说明，起修饰和描绘作用。 例如：
Jack, a diligent student, refused all help that was offered him. We all know the fact that Shakespeare is a great writer.
有时同位语也可位于与之同位的名词（本位语）之前。例如： ,
Formerly a worker himself, he is now an engineer. Normally a timid by , Tom saved the the drowning girl 2) 可充当同位语的词语
①名词、代词、数词 或名词词组作同位语。
Mr. Wang,my child's teacher, will be visiting us on Tuesday.（名词） They both come from Beijing.（不定代词）
You two went out to fetch water for us.（数词） |
Do you know the life of George Washington, the first president of the U.S.A. ?（名词词组） 说明：不定代词each作主语的同位语时,谓语动词要与主语的数保持一致。
They each have got a dictionary.他们每个人都有一本词典。 We each have the same desires.我们每个人都有相同的愿望。 ②形容词 作同位语。
All the people, old and young, went out to watch the match. All of us, Chinese and foreign，must obey the new law. ③介词短语作同位语。
The boy is standing there, under a big tree.
David,just back from Paris, was made monitor of our class. ④不定式作同位语。
There’s one thing he’ll never do --tell lies.
To commit an error, to make a mistake, is unavoidable. ⑤动名词作同位语（常用逗号隔开）。
Asking him to join us, that’s a good idea.
The first plan, attacking at night, was turned down.
turn sb/sth down 1. 调低〔烤箱的温度、收音机的音量等〕 2. 拒绝〔建议、要求或邀请
My hobby, swimming, dates from my childhood.
说明：?当名词，代词，数词或名词词组作同位语时，同位语的数并不影响句子谓语动词的数。例如：
His breakfast, milk, eggs and vegetables, is very good to health.
Everything we are now using -- books, pens, school-bags and so on --is provided by the public free of charge.
We each have a copy of English-Chinese dictionary. ?同位语必须与本位语的“格”保持一致。例如：
Three persons -- you he and I -- will have to maintain this big family.（主格） You may ask anyone --him, her or me.（宾格）
He is to inherit his grandmother’s, Lady Whitestone's property.（所有格） 3）表示同位关系的词语 ①表示等同关系： namely, that is(to say) , in other words
例如：You should consult an ophthalmologist, that is, an eye doctor. ②表示举例或列举： for example, such as, including
例如:We visited several cities, for example Rome and Paris. ③表示突出某点： especially, particularly, chiefly, mainly
例如：She wanted to invite many friends, especially Jane and Betty. 4） 下列表概括意义的抽象名词后常接同位语从句。
belief, evidence, conclusion, decision, suggestion, opinion, explanation，information，fact, hope，idea, view，news， possibility, problem, promise，question, truth，wish 例如： I have found the evidence that he was the criminal.
We all know the truth that the earth goes round the sun.
5） 同位语从句常用的关联词是that, whether。有时，根据含义也可用连接代词what, which（哪一个），who及连接副词how，when，why，where。引导同位语从句的疑问词前有时可加as to或of。
①关联词that,whether引导同位语从句
主句 同位语从句 His delay is due to the fact that the car went wrong halfway. We came to the decision that we must act at once. I have a small doubt (as to) whether he is suitable for the job. 说明：?关联词that在从句中不充当成分，不能用which替代，也不能省略。 ?个别名词后可接whether,在从句中不充当成分，仅说明其内容。 ②连接代词what, which, who引导同位语从句。 主句 I have no idea He always asks himself the question So far we have no news We don’t require additional knowledge We quarrelled over the question 同位语从句 what lies behind the mountain. what is to be done next. (as to) which route they have taken. (as to) which of the planets is older. (as to) who invented the acupuncture.针灸 说明：what用于泛指;which用于表达在特定范围内的“哪一个”；who常指人。 ③连接副词how, when, why, where引导同位语从句。 同位语从句 You have no idea I have no idea My question The problem how worried I was. when he will return. --that is,why he did it at all-- where we can get the machine Hasn’t been answered. has been solved. 说明：同位语从句也有限制性和非限制性之分。在非限制性同位语从句的句首，有时可以用namely, that is, that is to say 等同位指示词引导。 6）同位语从句常被分隔。
①谓语较短，可将谓语提前，修饰主语的同位语从句被谓语分割。 主句（主语为本位语） 同位语从句