PassageFourQuestions17to21arebasedonthefollowingpassage.DialogueisparticularlyeffectiveinteachingidiomaticEnglish.Weusethefollowingexercisewithstudentsatalllevels.Wepairupstudentsforthefirststageofwritingdialoguesandaskthemto"createascene."Theyhaveafewdaystothinkabouttheirsceneandtomeetwiththeirpartneroutofclass.Aftertheperiodofpreparation,thepairssitdownandworkouttheirdialoguealongwithitsscene.Theyusuallyprepareseveraldialogueswithsimilarcontentandthenhandinthebestonetotheteacher.Theteacherthenmeetsthepairstoexchangeideas,focusingonidiomaticlanguageuse.Thestudentsrevise(修改)untiltheirdialogueshaveanAmericanring.Asecondexerciseasksthestudentpairsto"produce"theirscenes,assigningtheirclassmembersascharactersandperhapsputtingtogethersomesimpleprops(道具).Sometimesoneclasswillpresentitsscenestoanotherclass.Weliketovideotapetheseproductionsforuseasteachingtools.Ingeneral,wehavefoundthatwritingdialoguebeforemovingintothespeakingstagehasmanyadvantagesandprovidesfeedback(反馈)fromtheteacherduringtheprocessofcreatingthescene.17.Theauthor,anEnglishteacher,askshisstudentstowritedialoguessothathisstudentscanbebetter__________.