【题目】A certain number of tourists________complaining about the high accommodation price recently.
A.is
B.are
C.has been
D.have been

【答案】D
【解析】考查时态和主谓一致。句意：在上个月有一些游客一直在抱怨住宿费太高。主语a certainnumber of tourists是复数；根据时间状语判断应用现在完成进行时。