直放站是一个全双工射频放大器，它是从归属基站的下行链路及从移动台的上行链路中接收、放大并（）该信号给移动台和归属基站。
参考答案：反向重传
《晋绥日报》
I ____ at my new novel when the big earthquake happened at 2:20 pm.
A．am working
B．was working
C．have worked
D．had been working
