如果再生用的30%工业盐酸中含有大量钠离子，则阳离子交换器再生后的出水钠离子将（）。
A.增大
B.降低
C.不变
D.先小后大
参考答案：A
实时传输MPEG-4流媒体文件采用的实时传输协议（RTP）基于传输层的（）协议而为用户提供服务的。
A．ICMP
B．UDP
C．IP
D．TCP
My parents _____ in Hong Kong. They were born there and have never lived anywhere else.
A．live
B．lived
C．were living
D．will live
