通过（）可对气层进行研究、压井、增产、堵水等井下作业。
A.气藏
B.气层
C.气井
D.地面工艺
参考答案：C
B．1︰1；1︰1
C．1︰1；1︰2
D．1︰2；1︰1
Einstein's Theory of Relativity is so________that most of us can not understand it. [ ]
A. controversial
B. abstract
C. appropriate
D. universal
