低层的信息系统解决（）问题。
A.结构化
B.半结构化
C.非结构化
D.半结构化和非结构化
参考答案：A
Life abroad was not easy for him, and it was several years before he ________ the whole community.
A．had been familiar with
B．got familiar with
C．have been familiar with
D．would be familiar with
属于压缩机气路系统检查内容的是（）
A.油泵出口压力
B.油箱液位
C.排气压力
D.冷却水压力
