超声波在人体什么组织中传播最快
A．皮肤
B．脂肪
C．肌肉
D．神经
E．骨
参考答案：E
解析：物质密度越大，超声波在其中传播速度越快。
－How did it that the secretary knew where we were?
－Maybe he had been following us.
A．come about
B．come across
C．come off
D．come round
最好与铁剂同时服用的药物是
A．维生素CB．维生素B1C．四环素D．抗酸药E．碳酸钙
