下列运算正确的是[ ]
A.x5+x5=x10
B.x5·x5=x10
C.(x5)5=x10
D.x20÷x2=x10
答案:B
220. Mr. Wang was reading ______ on how to learn a foreign language when someone came to see him.
A.paper
B.a piece of paper
C.a paper
D.a sheet of paper
IP城域网中窄带接入方式下利用PPP技术通过AAA服务器实现用户的身份认证并分配IP地址,使得用户能够通过接人服务器接入网络,进行信息的交互。()