以下哪个设备属于卫星地面站的下行射频设备（）
A.UPC
B.UC
C.HPA
D.LNA
参考答案：D
下列各项，与疼痛关系最密切的是
A．寒
B．风
C．湿
D．暑
E．燥
We firmly believe that war never settles anything. It only _____ violence. [ ]
A. runs into
B. comes from
C. leads to
D. begins with
