决定材料对X射线吸收量最重要的因素是（）
A.材料厚度
B.材料密度
C.材料原子序数
D.材料晶粒度
参考答案：C
—Would you like me to carry this box for you?
—_________.I can manage it myself.
A．No, thanks
B．It’s a pleasure
C．That would be nice
D．Yes, please
进气值
