快钻时或钻进放空的可能原因有低阻抗力地层、欠压实(异常压力)或()
A、火山岩
B、储层
C、致密砂岩
参考答案:B
We are deeply impressed by the goal from the conference the average income will double by the year 2020.
A.that
B.which
C.what
D.whose
简述收文登记的形式。