被广泛应用于农田排灌、工矿企业、城市给水排水和污水处理的泵是( )。
A．浅井泵B．潜水泵C．深井泵D．屏蔽泵
参考答案：B
According to the statistics, listening to loud music at rock concerts ______ hearing loss in some teenagers in the past 2 decades.
A．have caused
B．caused
C．had caused
D．has caused
对骨代谢影响最大的维生素是（）
A.维生素A
B.维生素B
C.维生素C
D.维生素D
E.维生素E
