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第七单元语法知识含有情态动词的被动语态（should,may,might,can,could,must)一、基本句型结构：1、肯定句：主语+情态动词+be+过去分词．．．．（+by...)eg:Teenagersshouldbeallowedtogoshopping.Tablescanbemadeofstones.Theworkmustbefinishedtoday.TheflowersmaybeplantedinFebruary.2、否定句：主语+情态动词+not+be+过去分词．．．．（+by...)eg:Teenagersshouldn’tbeallowedtogoshopping.Tablescan’tbemadeofstones.Theworkmustn’tbefinishedtoday.(mustn’t[ˈmʌsnt]:不能）Theflowersmayn’t[meɪnt]beplantedinFebruary.3、一般疑问句：情态动词+主语+be+过去分词．．．．（+by...)？eg:Shouldteenagersbeallowedtogoshopping?Yes,theyshould.No,theyshouldn’t.Cantablesbemadeofstones?Yes,theycan.No,theycan’t.Musttheworkbefinishedtoday?Yes,itmust.No,itneedn’t./No,itdon’thaveto.MaytheflowersbeplantedinFebruary?Yes,theymay.No,theymayn’t.4、特殊疑问句：疑问词+情态动词+be+过去分词．．．．（+by...)？eg:Whatshouldteenagersbeallowed?Whatcantablesbemadeof?Whenmustbeworkbefinished?Whenmaytheflowersbeplanted?二、含有情态动词的主动语态与被动语态的转换：eg:1).We（主语）can（情态动词）write（谓语）letters(宾语）inEnglish.（宾语补足语）Letters（主语）can（情态动词）bewritten（谓语）inEnglish(宾语）byus.（宾语补足语）2).Parents（主语）should（情态动词）allow（谓语）teenagers(宾语）tochoosetheirownclothes.Teenagers（主语）should（情态动词）beallowed（谓语）tochoosetheirownclothes(宾语）bytheirparents.（宾语补足语）3).You（主语）must（情态动词）clean（谓语）yourbedroom(宾语）everyday.(时间状语）Yourbedroom（主语）must（情态动词）becleaned（谓语）everyday(时间状语）byyou.(宾语）例题：1.Theoldpeopleshould___________(speak)topolitely.2.Anna__________(invite)tomybirthdayparty.3.Teenagersshould____________(allow)tosurftheInternet.4.Weshouldcleantheclassroomeveryday.（被动语态）Theclassroom________________________everyday.5.Eighteen-year-oldsshouldbeallowedtodrink.（否定句）Eighteen-year-olds_________________________allowedtodrink.6.Thelightsshouldbeturnedoffwhenyouleaveheclassroom.（主动语态）You___________________________thelightswhenyouleavetheclassroom.7.Whatschoolrulesdoyouthinkshouldbe___________(change)?