水的衰减系数是
A.0B.1C.2D.10E.100
参考答案:B
解析:水的X线吸收系数为1:致密骨为1.9~2.0,近于2.0;空气的吸收系数为0.0013,接近于0。
— He's never stolen anything before, he?
— . It's his third time to be taken to the police station. [ ]
A. hasn't; Yes
B. is; Yes
C. has; Yes
D. has; No
当代世界的主题是()。
A.战争与革命
B.民主与 * *
C.和平与发展
D.改革与开放