在地层圈闭中的油气聚集，称为（）油气藏。
A、地层超覆
B、地层不整合
C、油层
D、地层
参考答案：D
Classes were over. The students stopped __________. [ ]
A. have a rest
B. had a rest
C. having a rest
D. to have a rest
什么是客户服务观念？如何提升客户服务水平？
