若m是方程x2-2x-2=0的一个根,则2m2-4m+1=______.
原式=2m2-4m+1=2(m2-2m)+1,
∵m2-2m=2,代入得2×2+1=5.
Although many modifications have been made in it, the game known in the United States as football can be traced directly to the English game of rugby.
A.rules
B.changes
C.demands
D.leagues
按信令的作用区域划分()是电信网中各个交换节点之间传送的信令。
A.局间信令
B.用户线信令
C.随路信令
D.公共信道信令