问几个高中英语单选
1.Theresearchissodesignedthatonce_____nothingcanbedonetochangeit.A.beginsB.havingbegunC.beginningD.begun
2.Iwouldappreciate_____backthisafternoon.
A.youtocallB.youcallC.yourcallingD.you'recalling
3.Themanagersdiscussedtheplanthattheywoukdliketoosee____thenextyear.
A.carryoutB.carringoutC.carriedoutD.tocarryout
4.ThemayorofBeijingsaysthatallconstructionworkfortheBeijingOlympics_____by2006.
A.hasbeencompletedB.hascompletedC.willhavebeencompletedD.willhavecompleted.
主要是讲解书上没具体解释
鄙视下新申请的号分不多