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: 根据常识，公交车通常是往返于某一固定的线路，故选regular最合适。已知等差数列{an}满足4a3＝3a2，则{an}中一定为零的项是（　　 ）A.a6B.a7C.a8D.a9