在表达一个完整意义的句子里面只能有一个谓语动词，其余附属于该句的动词都应使用非谓语的形式。动词的非谓语形式有三种：动词不定式（todo），现在分词（doing），过去分词（done），可以在句子中作不同的成分，它们又有时态和语态的变化。不定式的时态变化：todo,tobedoing,tohavedone,tohavebeendoingtobedone,tohavebeendone不定式作状语不定式作状语时相当于一个状语从句，不定式作状语时往往用来作目的状语、结果状语或原因状语。目的状语：•Tobeawinner，youneedtogiveallyouhaveandtryyourbest.•Tocompletetheprojectintime，thestaffwereworkingatweekends.“为了......”•Bobtookdownmytelephonenumbersoasnottoforgetit.不定式用于so...asto...；such...asto；enoughto...；too...to；onlyto等结构中往往用来作结果状语:•Heissuchafoolastothinkthathisidlechattercaninfluenceothers.•Hehurriedtothebookingofficeonlytobetoldalltheticketshadbeensoldout.结果状语：•I'mtootiredtostayuplonger.不定式的被动态原因状语：不定式与形容词连用时，大多表示原因，用来作原因状语。这些形容词主要有：happy，kind，surprised，frightened，angry，shocked，glad，delighted，disappointed等。•I'mverygladtohearthenews.•I'monlytoogladtohavepassedtheexam.•YouwillneverknowhowhappyIwastoseeheryesterday.不定式的完成式注意：在“主语+系动词+表语（adj.）+todo”结构中，句子的主语与不定式有逻辑上的被动关系，且形容词表示主语的性质或特征，这时，需用不定式的主动形式表示被动意义。用于此种结构的形容词常有：easy,hard,difficult,important,impossible,interesting,pleasant,nice,comfortable,safe,dangerous等。•Thisquestioniseasytoanswer.•Thebookisdifficulttounderstand.现在分词的时态、语态变化：doing,havingdonebeingdone,havingbeendone过去分词无变化现在分词作状语主动、进行分词作状语时，分词的逻辑主语必须与句子的主语保持一致。分词作状语必须和句中主语含有逻辑上的主谓或动宾关系，否则一般不能使用分词作状语。Hearingthenews，theygotexcited.•Whentheyheardthenews,theygotexcited.→•Becarefulwhile/whenyoucrossthestreet.Becarefulwhile/whencrossingthestreet.→Havingbeentoldmanytimes，hestillrepeatedthesamemistake.•Thoughhehadbeentoldmanytimes，hestillrepeatedthesamemistake.→Havingbeenbittenbyasnake,shewasfrightenedatit.•Aftershehadbeenbittenbyasnake,shewasfrightenedatit.→现在分词的完成被动态过去分词作状语被动、完成•Theteachercameintothelab，followedbysomestudents.Givenachance，Icansurprisetheworld.•IfIamgivenachance，Icansurprisetheworld.→•Whenoneisofferedhelp,oneoftensays“Thankyou”or“It'skindofyou”.→Whenofferedhelp,oneoftensays“Thankyou”or“It'skindofyou”.复习：with复合结构with复合结构表伴随todo将来doing主动、正在进行done被完成•Withsomuchworktodo，Ican'tgoswimmingwithyou.•Withsomanypeoplelookingather，shefeltnervous.•Withtheirworkfinished,theywenthome.•Istoodbeforeherwithmyheartbeatingfast.独立主格结构非谓语动词作状语时，它的逻辑主语往往与句子主语保持一致。但有时非谓语动词带有自己的逻辑主语，在句子中作状语，我们称之为独立主格结构。•Lotsofhomeworktodo，Ihavetostayhomeallday.•Manythingstosettle,themanagerlooksworried.todo表将来•Theguideleadingtheway，wehadnotroublegettingoutoftheforest.•Thequestionbeingdiscussed，amancameupwithapracticalsolution.现在分词（doing）表主动、进行•Rexwaslisteningattentivelytothelecture，allhisattentionfixeduponit.•Manythingssettled，themanagerlooksrelaxed.过去分词（done）表被动、完成
