句子的构成概说1、任何一个句子一定由主语（Subject，简写成S）及动词（Verb，简写成V）构成。例：John works hard. （约翰努力工作。） S VHe plays the piano well. （他钢琴弹得很好。）S VMary seems to be fond of learning English. （玛丽似乎喜欢学习英语。）S V2、（1）有时主语可以省略，而构成祈使句。这种祈使句由原形动词（也称为动词不定式）引出。例：Work hard! = （You should）work hard.（努力工作！）原形VBe quiet! =（You should）be quiet. （安静！）原形V（2）祈使句变成否定型式时，要在原形动词前加 Dont。例：Dont fool around. （别游手好闲。）Dont be silly. （别傻了。）第一节 可充当主语的词类一般所见到的句型中，通常是以名词做主语，但除了名词以外，还可以用代词、动词转变过来的动名词或不定式短语、名词从句、名词短语、表距离的地点副词短语等做主语。介绍如下：一、名词做主语例：The child is apt to tell lies.（这孩子喜欢说谎。）Gold is of much value.（黄金很值钱。）二、代词做主语例：He always keeps his promise.（他总是信守承诺。）It is quite interesting to climb mountains.（爬山蛮好玩的。）三、动名词或不定式短语做主语动词绝不可直接充当主语，一定要变成动名词或不定式短语，如此才可视为名词的对等语，当主语用。例：See him makes me angry. （，See为动词）Seeing him makes me angry. （，Seeing为动名词）（看到他就让我生气。）See him is my purpose of coming here. （，See为动词）To see him is my purpose of coming here. （，To See为不定式）（我来这儿是为了看他。）1动名词做主语用动名词做主语，通常用以表示已知的事实或经验。试译下句中的主语：集邮是他的嗜好之一。由“嗜好”一词得知，此处的“集邮”乃是一种经验。故应译成动名词 Collecting Stamps，而成：Collecting stamps is one of his hobbies.再译下句中的主语：听音乐使我快乐。由“使我快乐”得知，“听音乐”是说话者曾经做过的事，故仍用动名词短语Listening to music 做主语，而成：Listening to music makes me happy.2不定式做主语用不定式做主语时，通常表示一种意愿、目的或未完成的事。试译下句中的主语：出国念书是我最大的愿望。由“愿望”一词得知此处的“出国念书”乃是一种意愿或尚未做的事，故应以不定式短语 To study abroad 充当主语，而成：To study abroad is my greatest desire.（出国念书是我最大的心愿。）再译下句中的主语：到日本游玩是我今年的计划。由“计划”一词得知说话者尚未到过日本游玩（go to Japan for a visit）,故此处用不定式短语 to go to Japan for a visit 做主语，而成：To go to Japan for a visit is my plan for this year.注意：不定式或动名词短语做主语时，往往会形成主语过大的现象，故通常均用代词it做主语，置于句首，而将真主语（亦即不定式或动名词短语）移至句尾。动名词移至句尾时，通常改为不定式短语。例：Collecting stamps is one of his hobbies.= It is one of his hobbies to collect stamps.虚主语真主语Listening to music makes me happy.= It makes me happy to listen to music.虚主语真主语To study abroad is my greatest desire.= It is my greatest desire to study abroad.虚主语真主语注：虚主语相当于传统语法中的形式主语。注意：被it代替的动名词短语移至句尾，仍保留动名词形态而不变成不定式短语。但此种用法并不普遍，初学语法者宜尽量避免。例：It is interesting to learn English. （佳）It is interesting learning English. （劣）注意：以下句型则属例外情形，it要代替动名词短语，不可使用不定式短语：It is no use + 动名词短语例：It is no use crying over spilt milk.(覆水难收。)It is no use asking him for help.(向他求救是没有用的。)注意：It is no use + 动名词短语= It is useless + 不定式短语= It is of no use + 不定式短语use= There is no sense + in + 动名词短语point例：It is useless to cry over spilt milk.= It is of no use to cry over spilt milk.= There is no use in crying over spilt milk.四、名词从句做主语1名词从句他不用功令我生气。这个句子的主语虽然是“他不用功”，但若译成 He doesnt work hard，则大错特错。He doesnt work hard makes me angry. （）因为 He doesnt work hard 是句子。所谓句子，就是一开头就是主语的结构（此处的He就是主语）。句子绝不能当主语，一定要变成名词从句方可做主语。故本句的正确译法应为：That he doesnt work hard makes me angry. （）名词从句2名词从句的种类名词从句一共有三种：that从句、whether从句、疑问词所引导的从句（1）that从句任何一个主语起首的句子前面冠以that即成that从句。He doesnt believe my words. that he doesnt believe my words（他不相信我说的话。）He enjoys dancing. that he enjoys dancing（他爱跳舞。）There is much work to do. that there is much work to do.（有很多工作要做。）（2）whether从句本从句是由可用yes/no回答的问句变化而成。 问句有be动词时：主语与be动词还原，前面冠以whether。例：Is he happy? whether he is happy（他是否快乐） 问句有一般助动词（can, will, may, should, ought to, must, have）时：主语与助动词还原，前面冠以whether。例：Can he do it? whether he can do it（他是否能做这件事）Has he done it? whether he has done it（他是否已做好这件事） 问句有do, does, did等助动词时：主语与助动词还原，再将do，does，did去掉，后面的动词依人称和时态变化。例：Did he come? whether he did come came（did为过去式，故come改为came） whether he came（他来不来）Does he like it? whether he does like itlikes（does为第三人称单数现在式，故like改为likes） whether he likes it（他喜不喜欢它）（3）疑问词从句本从句是由疑问词（when，what，how，where，why）等引导的问句变化而成。 问句有be动词时：主语与be动词还原，前面保留疑问词。例：What is he doing? what he is doing（他正在做什么） 问句有一般助动词时：主语与助动词还原，前面保留疑问词。例：Where can he find it? where he can find it （他在哪里能找到它） 问句有do，does，did等助动词时：主语与助动词还原，前面保留疑问词，再将do，does，did去掉，动词依人称和时态变化。例：What did he write? what he did writewrote（did为过去式，故write改为wrote） what he wrote（他写什么）When did he come? when he did comecame（did为过去式，故come改为came） when he came（他何时来）How does he do it? how he does do itdoes（does为第三人称单数现在式，故do改为does） how he does it（他怎么做这件事）注意：who，what，which（哪一个）为疑问代词，若在问句中做主语，变成名词从句时，结构不变。例：Who came here? 问句主语 who came here 名词从句（谁来这儿）What happened last night? 问句主语 what happened last night（昨晚发生什么事）Which was bought? 问句主语 which was bought 名词从句（哪个被买走）3名词从句的功能我们已知，名词从句是由叙述句子或问句变化而成，和动名词或不定式短语一样，名词从句也要被视为名词。由于具有名词的特性，故可做主语、谓语或be动词之后的补语。（1）名词从句做主语例：That honesty is the best policy is a proverb (Which) we should always keep in mind.主语（“诚实为上策”是一句我们应时时谨记在心的箴言。）Where he lives is still a doubt.主语（他住哪里仍不确定。）Whether he can do it remains to be seen.主语（他能胜任与否仍优待观察