钻井取心分类是按（）来定义的。
A、循环钻井液类型
B、取心工具
C、取心钻头
D、取心手段
参考答案：A
—I've read another book this week.
—Well, maybe _____ is not how much you read but what you read that counts. [ ]
A. this
B. that
C. there
D. it
1303轴承内径的尺寸为（）。
A.17毫米
B.15毫米
C.12毫米
