1.主语从句1）主语从句可直接位于主语的位置,如果从句较长,谓语又较短,可用it作形式主语,而将从句放在句末.常见的句型有：*Itisafactapityaquestiongoodnewsthat...2)what引导的主语从句表示“...的东西时”,一般不用it作形式主语.Whatwelackisexperience.3)what,who,when,why,whether等词含有各自的疑问意义,但它们引导的主语从句,都用陈述语序.Howtheplanistobecarriedoutshouldbediscussedagain.2.宾语从句1）宾语从句可位于及物动词、介词和某些形容词后.连词that常可省略.介词后一般接疑问词引导的宾语从句.inthat(因为),exceptthat(除了),butthat(只是）已构成固定搭配,其他介词后一般不接that引导的宾语从句.*IpromisedthatIwouldchangethesituation.2.宾语从句1）宾语从句可位于及物动词、介词和某些形容词后.连词that常可省略.介词后一般接疑问词引导的宾语从句.inthat(因为),exceptthat(除了),butthat(只是）已构成固定搭配,其他介词后一般不接that引导的宾语从句.*IpromisedthatIwouldchangethesituation.3.表语从句表语从句出现在结构为“主语+系动词+表语从句”的句子中.表语从句除可用that,what,when,why,whether,how等引导外,还可由because,asif(though)等引导.that常可省略.如主句主语为reason,只能用that引导表语从句,不可用because.PerhapsthemostimportantthingtorememberisthatthereisnoonecommontypeoflifeinAmerica.2)宾语从句后如有宾补,要用形式宾语it来代替,而把宾语从句移至宾补之后.Hehasmadeitclearthathewouldnotchangehismind.4.同位语从句同位语从句用于对前面出现的名词作进一步说明,一般用连词that引导,由于先行名词的意义不同,也可用whether,who,when,where,what,why,how等引导.常见的先行名词有fact,idea,belief,news,hope,conclusion,evidence,suggestion,order,problem,report,decision.有时由于谓语较短,将同位语从句位于谓语之后.Shefinallymadethedecisionthatshewouldjointhefashionshow.5.定语从句定语从句所修饰的先行词可以是名词或代词,也可以是一个句子.定语从句通常位于先行词之后,由关系代词或关系副词引导.*限制性定语从句限制性定语从句修饰先行词,对先行词起修饰作用,紧接先行词之后,无逗号,若省去,原句意思不完整.引导定语从句的关系代词有who,whom,whose,which,that等.who,whom,whose用于指人,whose有时也可指物,相当于ofwhich；which用于指物；that既可指人也可指物,但只用于限制性定语从句中.关系代词除了引导定语从句,替代先行词外,还在从句中担任主语、宾语、定语等.ThecomputersandcableswhichmakeuptheInternetareownedbypeopleandorganizations.Thosewholivealoneorwhoaresickmayhavetroubleingettingclosetootherpeople.Thegirlwhoseparentsdiedinanaccidentislivingwithhergrandmother.1)当先行词是all,anything,everything,something,nothing等不定代词或先行词前有first,last,any,few,much,some,no,only以及形容词最高级修饰时,只能用关系代词that引导从句.ThatisallthatI'veheardfromhim.He'sthefirstpersonthatI'mgoingtointerviewthisafternoon.2)关系代词的省略在从句中作宾语的关系代词常可省略.关系代词紧跟介词,作介词宾语时不可用that,只可用which或whom引导从句,并且不可省略,但当介词位于宾语从句句末时,作为介词宾语的关系代词仍可用that,也可省略.Thisisoneofthosethingswithwhichwehavetoputup.Thisisoneofthosethings(whichthat)wehavetoputupwith.3)引导定语从句的关系副词有when,where,why等.关系副词在从句中作状语,意义上相当于一个“介词+which”的结构.Evenincomicbookswhere(=inwhich)therearenowords,thestoriesarefullyexpressedthroughthedrawings.Nooneknowsthereasonwhy(=forwhich)hewassoangrythatday.6.状语从句*时间状语从句引导时间状语从句的从属连词和词组有：1）when,whenever,while,as,after,before,since,till,until,once等.Wehavelearntquitealotaboutitsincewecamehere.2)assoonas,hardly(scarcely)...when,nosooner...than,each(every)time,themoment,immediately(that)等.AssoonasIsentane-mailmessage,Ireceivedpositiveresponses.Themomentheheardthegoodnews,hejumpedwithjoy.*地点状语从句引导地点状语从句的连词是where,wherever.Wherevershewent,shetookherlittledaughterwithher.*原因、结果和目的状语从句1）引导原因状语从句的从属连词有：because,as,since,now(that),seeingthat,consideringthat,inthat等.Consideringthatheisafreshman,wemustsayheisdoingwell.2)引导结果状语从句的连词有：so...that,such...that,sothat,that,so等.MickeyMouseissoattractivethatthechildrenarereluctanttoleave.3)引导目的状语从句的连词有：sothat,inorderthat,forfearth