某给定物质对连续X射线而言，其线衰减系数（）。
A.是一个常数
B.是一个变数
C.随物质厚度的增加而减小
D.A和B全对
参考答案：C
—Excuse me, ______?
—It's next to the library. [ ]
A. is this the bank
B. is there a bank here
C. where's the bank, please
D. does your father work in a bank
牙齿Ⅱ度松动是指
A．用力摇动时有轻微动度B．颊舌向及近远中向均有动度C．颊舌向有动度D．近远中向及垂直向有动度E．颊舌向及垂直向有动度
