AP无线回传接口，用于室外时射频接口应为（）型。
A.N
B.F
C.SMA Male
D.SMA FMale
参考答案：A
----Can he work out the maths problem?
----I think _____ hard for him to work it out.
A．it’s
B．that’s
C．this is
D．they’re
