if四种条件句

FIRSTSECONDTHIRDZEROIfIamlateforschool,myteachergetsangry.IfclauseMainclauseIf+PresentsimplePresentsimpleIfIoversleep…Imissthebus.IfImissthebus,Iamlateforschool.IfIamlateforschool,myteachergetsangry.IfIgotoLondon,IwillseetheBigBen.IfclauseMainclauseIf+Presenttensewill/can/may/must+verb•IfIgotoLondon…IwillseetheBigBen.IfIgotoBuckinghamPalace,IcantakeaphotooftheRoyalGuard.IfyougotoLondon,youmustlookrightbeforecrossingastreetIfclauseMainclauseIf+PastSimplewould/could/might+verbIfIwereanastronaut,Iwouldtravelinaspaceship.IfIwereanastronaut,Iwouldtravelinaspaceship.IfItravelledinaspaceship,IwouldgotoMars.Nicetomeetyou!IfIwenttoMars,IwouldmeetaMartian.IfImetaMartian,Iwouldn’tunderstandhim.?IfIavedIfIdidn’tunderstandhim,IwouldcomebacktotheEarth.IfIhadstudiedhard,Iwouldhavepassedmyexams.IfclauseMainclauseIf+PastPerfecttensewould/could/might+have+pastparticipleIIfyouhadstudiedhard,youwouldn’thavefailedyourexam.IIfyouhadpassedyourexam,youcouldhavegonetothebeach.IIfIhadgonetothebeach,Iwouldhavemadesandcastles.