用户网络接口的呼叫控制消息的协议识别符是（）。
A.00010000
B.00001000
C.10000000
D.10001000
参考答案：B
My brother has _____ in Japan. [ ]
A. pen pal
B. a pen pal
C. two pen pal
D. a pen pals
叩诊
