确定地层压力时,(),井眼周围的地层压力才恢复到原始地层压力。
A.关井后待套压稳定
B.关井后10~15min
C.关井后待立压稳定
D.关井15min
参考答案:C
She walked home by herself at night, _____ she knew that it was dangerous.
A.once
B.as
C.unless
D.although
当采集站在炮井附近放炮时采集站应放在炮井的()。
A.上风方向
B.下风方向
C.左边
D.右边