在钻井中靠适当的钻井液柱的压力平衡地层压力的方法是（）。
A.一级井控
B.二级井控
C.三级井控
参考答案：A
I saw a woman running toward me in the dark.Before I could recognize who she was，she had run back in the direction______ she had come.
A．of which
B．by which
C．in which
D．from which
大乘佛教和小乘佛教的经典，就要包括（）
A、经藏
B、典藏
C、律藏
D、论藏
E、议藏
