骨显像时,一般成骨性病变部位的放射性可表现为()
A.老年人膝部增高
B.对称性增浓
C.显影异常清晰,双肾不显影,放射性降低
D.浓聚
E.闪烁现象
参考答案:B, D, E
This took place in the ______ .
A.1940
B.1940s
C.1940es
D.1940th
真空泵为什么需要配备真空罐和水封罐?