—Has Judy returned from Hong Kong? I’d like to meet her.

—I’m sorry, but she _______ back here only for last weekend.[ ]

A. has been    

B. was     

C. had been   

D. would be

一颗静止卫星通信线路的上行频率为6GHz，下行频率为4GHz，若地球站与卫星的距离为40000KM时，则上行线路在自由空间损耗为（）DB。

A.200.05

B.196.53

C.169.47