初中英语语法总结（从句）

 第三节  从句
    从句分为定语从句，状语从句和名词从句三大类。定语从句又分为限定性和非限定性从句两种，由关系代词或关系副词引导，修饰主句的某个成分。状语从句分为时间、结果、让步、原因、条件及行为方式状语从句。名词从句包括主语、宾语、表语和同位语从句及there be句型。
1．定语从句
    限定性定语从句中that可代表人和事，而which只代表事；二者在从句中作主语或宾语。that作宾语时常可省略，which则不能，而且其后的“不及物动词+介词’’中的介词不能省略。which作宾语时，先行词与which之间的介词不能省。例如：
1.The first doll that could say“mama”was invented in 1830．
2.The second half of his voyage was by far the more dangerous part，during which he sailed round the Cape Horn．
代表a11，anything，something，nothing，much等词时，用that而不用which，that作宾语可省略。例如：
1.I care anything that has something to do with it．      
2.You'd better do something he prefers to do to please him． 
3.That is the last time we met each other．
4.I came across the woman you told me about yesterday．
who和whom引导的从句用来修饰人，分别作从句的主语和宾语。where是关系副词，用于表示地点的定语从句，而when用来表示时间。whose是关系代词，修饰名词作定语。例如:
1.Henry Ford is the person who is most responsible for developing the idea of mass production．
2.The knee is the joint where the thigh bone meets the large bone of the lower leg．
3.The next morning, when she came down to breakfast , Mary was beaming with the pleasure of a new，great discovery．
4.The visiting professor is a famous scientist whose son studies in my department．
在下列情况，限定性定语从句的关系代词可以省略：

1)当关系代词在从句中作宾语或表语；或它们在从句中作介词的宾语，而该介词又在句末时；

2)当先行词是that，all，only，everything，something，nothing等代词时，或先行词前有一个最高级形容词修饰时；

3)当先行词前有only，any，all，first，no，last等修饰时，或先行词就是time，moment，way(anyway)，direction，distance等名词时，关系代词即可省略。例如：
1.The delegation we had been waiting for finally arrived．
2.I met the woman you told me about．
3.She gave me all she could afford．
4.With TV we can see things happen almost at the exact moment they are happening．
非限定性定语从句，其作用为：对所修饰的成分作进一步的说明，它与主句用逗号隔开。此类从句省略后其余部分仍可成立。在非限定性定语从句中，which可代表前面的整个句子；代表人时只能用who，whom，而不能用that；as也可用作关系代词。例如:
1.The telephone，as we know，was the invention of Alexander Graham Bell．
2.The Little White House in Warm Springs was the Georgia home President 3.Franklin D．Roosevelt，who died there on April 12，1945．
4.Living in a damp house for a long time is harmful to one’s health，which  is known to everyone．
2．状语从句
状语从句可分为：时间状语从句(主要由when，whenever，after，before，a5，slnce，once，assoonas，Until，while等连词引导)，结果状语从句(由so…that和such…that连接)，让步状语从句(由though，although, no matter，even if, however，whatever等词引导)，原因状语从句(由as，because，since和for引导)，条件状语从句(由if, whether，as long as，provided that等词引导)，地点状语从句(由where引导)，行为方式状语从句(由as引导)。有时条件状语从句中，主句不可以用将来时，而用一般时代替。例如：
1.The small greenish flowers of the elm tree appear in the Spring, long before the leaves grow.
2.QiongYao's novels used to be so popular that her books appeared on best-seller lists.
3.Gas balloon is less safe than hot balloon because it may catch fire.
4.Uniform acceleration (同样的加速) occurs if the rate of change remains the same over successive equal intervals of time．  
5.Thousands of Chinese college students went to the US Consulate 6.Shanghai，where they protested NATO's bombing at China's Embassy in Yugoslavia.
状语从句中的 “主语+be”可以省略，前提是：从句主语和主句主语一致，且从句谓语“be”省略后的结构为“连词+现在分词／过去分词介词短语／形容词／名词短语”。) 例如：
1.When well fitted, glasses can correct most sight defects in healthy eyes．
2.If necessary，I would like to see you in your office.   
3.Although seriously wounded，he never complained．
3．名词从句
名词从句包括主语从句、宾语从句，其中有介词与形容词的宾语从句、表语从句和同位语从句。
1）主语从句
主语从句常出现在it is+名词、形容词、分词+主语从句”的形式中。例如：
1.It is reported that Taiwanese pop singer Meng Tingwei will hold a solo concert in Shanghai someday this month．
2.It must be pointed out that you have failed to meet the deadline．
3.It usually happened that I was late because of traffic jams.
主语从句还可用when，where，how，why，whether等连接副词，和who，whom，whose，what，which，whoever，whatever，whichever等连接代词来引起。例如：
1.How to arrange the meeting is not your task．
2.Whose candidate will win the election is the question both political parties are asking．
3.When I leave is my own decision.
4.Whoever will go to the party won't change my mind of staying at home．
2)宾语从句
宾语从句可由that, 疑问代词或副词how，why和where等引出。例如：

1.To postpone the conference until next month indicated that they were unprepared．
2.Nearly a11 the staff agreed with what I said．
3.Everyone worried about her because no one was aware of where she had gone．
4.Could you offer more details except that it happened at night?
由what，whether，how引导的宾语从句可用在介词后，而由that引导的从句只跟but，besides，except，in, save之后。例如:
1.I can hardly believe in what they have done.
2.He doesn’t know my phone number except that the city code is 021.
一些表语性的形容词，如：alarmed，amazed，annoyed，astonished, certain，confident, disappointed, glad, pleased, proud, sad, shocked, sure, surprised, worried, ect.做表语时，后面可跟由that, how等引导的宾语从句。例如：
1.I was amazed how he could pass the exam without attending the lectures．
2.He is confident that he will pass the Band 6 examination．
3.She was surprised how simple his problem is．
4.We are all pleased that he will be able to pass the final examination.
3)表语从句   
表语从句对主语的内容起解释和阐述的作用；若表语从句用that引起，that起连接作用，不能省略。b表语从句也可用连接词how，when，where，why，what引起。由because引起的表语从句通常只用在“this／that／it is because” 结构中。例如：
1.A logarithm(对数) is what is known in algebra exponent(代数的指数)．
2.One thing I admire most about them is that they are hospitable．
3.She works too hard；That is why she is exhausted．
4.I must point out that where you intend to build a super-market is where the elderly do exercise every day．
4)同位语从句
同位语从句是由两个或两个以上同一层次语言单位组成的结构，其中前项与后项所指相同，句法功能相同。同位语从句由that引导，也可由whether，how，why，where, when等来引导。例如：
1.She ignored the teacher's instruction that she must study hard．
2.The question whether or not I should help him in such a case troubled me greatly．