什么叫防爆安全型设备?
参考答案：防爆安全型设备正常时不产生火花、电弧或危险温度，并在设备上采取适当措施，以提高安全性能。
肾小管髓袢升支的功能主要是
A．重吸收溶质
B．重吸收水
C．重吸收水而不重吸收溶质
D．水与溶质均重吸收
E．水与溶质均不重吸收
Stretchers are fitted in lifeboats to provide a（）.
A.place for people to lie down
B.means for rigging the sail
C.place for rowers to brace their feet
D.suitable means for water to drain below the footings
