Serving GW和PDNGW合称是()
A.PDSN
B.SGSN
C.GGSN
D.SAE-GW
参考答案:D
计算:5x(2x+1)—(2x+3)(5x—1)
6,13,22,35,54,81,( )。
A.115
B.117
C.118
D.116