对半值层的描述错误的是()
A.可以表示X射线质
B.即HVL
C.可以用mmAl表示
D.反映了X线束的穿透能力
E.对同一物质来说,半值层大的X线质软
参考答案:E
A 7-year-old boy is hospitalized with cystic fibrosis. To help him manage secretions and avoid respiratory distress, the nurse should
A. perform chest physiotherapy every 4 hours.B. give pancreatic enzymes as ordered.C. place the child in an oxygen tent and have oxygen administered continuously.D. serve a high-calorie diet.
桥式起重机故障中,属于大车运行机构故障的有:()。
A、桥架歪斜运行、啃轨
B、个别滑轮不转动
C、小车三条腿运行
D、减速器整体发热
E、制动器不松闸
F、定子局部过热
G、电动机在工作时振动
H、交流电磁铁工作时声响大
I、控制器合上后电动机不转
J、起重机运行中经常掉闸