—How long have these archaeologists stayed in this village?( ) —Not long, just ________ this Monday. A. on B. until C. after D. since 答案:D 考查介词。依据问句可知是现在完成时,而A、B、C三个选项都不能与现在完成时连用,只有since与过去时间点连用时用现在完成时,故D正确。 如图,在△ABC中,AB=AC=5,P是BC边上除点B、C外的任意一点,则AP2+PB•PC=________.