CP-3B司机控制盒发码信号输出端输出阻抗为≥()。
A.1KΩ
B.2KΩ
C.5KΩ
D.10KΩ
参考答案:D
维生素D缺乏性手足搐搦症患儿血清钙离子浓度低于()
A.1.0mmol/L
B.1.75mmol/L
C.1.88mmol/L
D.4mmol/L
E.7mmol/L
Jack opened the door;________stood a woman he had never seen before.