题目

A new ________ bus service to Tianjin Airport started to operate two months ago. A. normal                B. usual                C. regular                   D. common 答案：C 解析: normal正常的( normal temperature, return to normal); usual通常的（usual time, usual restaurant); regular定时/期的，有规律的（regular breathing; a regular bus service ）; common一般的，常见的（common sense, common names）。若a，b∈R+，设A=+，B=，则A与B的大小关系是    ．