高考英语精品同步备课课件 英语 外研版（2019）选择性必修二 Unit4 Using language.pptVIP

Unit4BreakingboundariesLookatthesentencesandanswerthequestions.Sentences(a)and(c)arefromthereadingpassage.1Whatdoes“it”refertoinsentences(a)and(c)?2Whydoestheauthorchoosetousesentences(a)and(c)insteadof(b)and(d)?aButitisvitalnottotakeanychances.bButnottotakeanychancesisvital.cItisimportanttorememberthatEboladoesn’trespectnationalboundaries.dTorememberthatEboladoesn’trespectnationalboundariesisimportant.Thefirstsentencesineachgroupuse“it”asanemptysubjectatthebeginningofthesentences.Thereasonwhysentences(a)and(c)arechosenisthatthesentencesarekeptbalancedandthekeyinformationofthesentencesisemphasised.Nowlookformoresentenceswiththisstructureinthereadingpassage,andsummariseitsuseinyourownwords.Ifeltitwasmydutyasadoctortogothereandoffermyhelp.ItissoinspiringtohavecolleagueslikeWilton,MaisyandAlfonso,......,itisabsolutelyessentialforusalltocollaboratetocreateaglobalcommunitywithasharedfutureofpeaceandprosperity.ItasanemptysubjectIt作形式主语通常it作为形式主语，在句中没有实际意义，只是满足语法需要，起到一个平衡句子结构，避免句子头重脚轻的作用。概念把下列的句子变成用it的形式主语句。1.Tosaygoodbyeisdifficultforme.Itisdifficultformetosaygoodbye.2.Playingtoomanycomputergamesisawasteoftime.Itisawasteoftimeplayingtoomanycomputergames.Itisobviousthatheisclever.3.Thatheiscleverisobvious.ItasanemptysubjectIt作形式主语类型通常it代替不定时、动名词、从句充当主语，起到一个平衡句子结构，避免句子头重脚轻的作用。类型1.代表不定式(1)It+be+形容词+不定式Itisdifficulttotranslatethebook.(2)It+be+名词+不定式Itwasherdutytocleantheroom.(3)It+be+介词短语+不定式Itwasagainstmyprincipletodothat.(4)It+及物动词+宾语+不定式Itcost150yuantobuythedress.在“It＋be＋形容词＋for/ofsb.todosth.”句型中，如果形容词描述的是sb.，则应用介词of；如果描述的是todosth.就用for。Its