1.Itisn'tcoldenoughforthere____afrosttonight,soicanleavehiscaroutquitesafely.A.wouldbeB.beingC.wasD.tobe2.Thenumberofregisteredparticipantsinthisyear'smarathonwashalf________.A.oflastyear'sB.thoseoflastyear'sC.of

　　1.Itisn'tcoldenoughforthere____afrosttonight,soicanleavehiscaroutquitesafely.

　　A.wouldbeB.beingC.wasD.tobe

　　2.Thenumberofregisteredparticipantsinthisyear'smarathonwashalf________.

　　A.oflastyear'sB.thoseoflastyear's

　　C.ofthoseoflastyear'sD.thatoflastyear's

　　3.Iwouldhavegonetovisithiminthehospitalhaditbeenatallpossible,butI____fullyoccupiedthewholeoflastweek.

　　A.wereB.hadbeenC.havebeenD.was

　　(此题为何不能选B?)

　　第三题是选B，为什么不能选D？