LTE系统中，X2接口是eNB与下面哪个网元的接口（）
A.MME
B.ENB
C.RNC
D.SGSN
参考答案：B
There are _____ of students in our school but only _____ of them are girls. [ ]
A. hundred; two hundred
B. hundreds; two hundreds
C. hundreds; two hundred
简述咽囊的演变。
