定语从句是由关系代词和关系副词引导的从句，其作用是作定语修饰主句的某个成分，定语从句分为限定性和非限定性从句两种。状语从句分为时间状语从句，结果状语从句，让步状语从句，原因状语从句，条件状语从句以及行为方式状语从句。名词从句包括主语从句，宾语从句，表语从句和同位语从句及therebe句型。一、限定性定语从句1.that即可代表事物也可代表人，which代表事物；它们在从句中作主语或宾语，that在从句中作宾语时常可省略关系词，which在从句中作宾语则不能省略。而且，如果which在从句中作“不及物动词＋介词”的介词的宾语，注意介词不要丢掉，而且介词总是放在关系代词which的前边，但有的则放在它原来的位置2.which作宾语时，根据先行词与定语从句之间的语义关系，先行词与which之间的介词不能丢3.代表物时多用which，但在带有下列词的句子中用that而不用which，这些词包括all,anything,much等，这时的that常被省略4.who和whom引导的从句用来修饰人，分别作从句中的主语和宾语，whom作宾语时，要注意它可以作动词的宾语也可以作介词的宾语5.where是关系副词，用来表示地点的定语从句6.when引导定语从句表示时间〔注〕值得一提的是，表示时间“time"一词的定语从句只用when引导，有时不用任何关系代词，当然也不用that引导BythetimeyouarriveinLondon,wewillhavestayedtherefortwoweeks.IstillrememberthefirsttimeImether.Eachtimehegoestobesinesstrip,hebringsalotoflivingnecessities,suchastowers,soap,toothbrushetc.7.whose是关系代词，修饰名词作定语，相当于所修饰成分的前置所有格8.当从句的逻辑主语是some,any,no,somebody,anybody,nobody,something,anything,everything或nothing时，常用thereis来引导二、非限定性定语从句：非限定性定语从句的作用是对所修饰的成分作进一步说明，通常和主句间用逗号隔开，将从句拿掉后其他部分仍可成立1.which引导的非限定性定语从句来说明前面整个句子的情况或主句的某一部分2.在引导限定性定语从句时，that有时相当于inwhich,atwhich,forwhich或atwhichAttitudestowardsdaydreamingarechanginginmuchthesamewaythat(inwhich)attitudestowardsnightdreaminghavechanged.人们对白日做梦的态度正在改变，这与人们对夜间做梦的看法的变化有非常相似之处。Ilikethemusicfortheveryreasonthat(forwhich)hedislikeit.我出于某种原因喜欢这种音乐，而他恰恰与我相反。Wearrivedthedaythat(onwhich)theyleft.刚好我们到的那天他们走了。3.有时as也可用作关系代词4.在非限定性定语从句中，不能用that，而用who,whom代表人，用which代表事物定语从句中只用THAT,不用which的情况1.当先行词是不定代词，如all,everything,anything,nothing,much,few,little,none,theone等AllTHATcanbedonehasbeendone.Ididn'twantthisrecorder;IwanttheoneTHATwasborrowedyesterday.2.先行词（指物的）前面有only,few,oneof,little,no,all,every,very等词修饰时There'snodifficultyTHATwecan'tovercome.I'vereadallthebooksTHATcanbeborrowedhere.ThisistheverymanTHATIwanttosee.3.先行词被序数词first,last,next等或形容词的最高级修饰时ThisisthefirstletterTHATI'vewritteninEnglish.SheisthemostcarefulgirlTHATI'veeverknown.4.当先行词既有人又有物时TheytalkedaboutthepeopleandplacesTHATtheyhadvisited.5.当先行词是系动词be后面表语或关系词本身是从句的表语时Shanghaiisn'tthecityTHATitusedtobe60yearsago.HeisnolongerthemanTHATheusedtobe.6.当主句是以who,which或what开头的特殊疑问句时WhoisthemanTHATiswaitingattheschoolgate?WhichisthecarTHATranoveradogyesterday?WhatdidyouseeTHATmadeyousoangry?7.当主句以Therebe…结构开头时，或关系代词在therebe…结构中作实义主语，先行项为物ThereisaseatinthecornerTHATisstillfree.TherearetwobooksonhistoryTHATareforyou.The9.15isthefastesttrainTHATtherehaseverbeen.8..当先行词是基数词时YesterdayIcaughttwofishandputtheminabasinofwater.NowyoucanseethetwoTHATarestillalive.
