If the operation ________ carefully prepared, it would not have been successful.
C
语法题:虚拟语气。
Aftermonthsofvoyage,Columbusarrivedin______laterprovedtobeanewcontinent.
IsitShakespeareTheatre_______youaregoingtowatchtheplayTheMerchantofVenice?
Iftheoperation________carefullyprepared,itwouldnothavebeensuccessful.