[配置路由器信息]
Current configuration：
!
hostname router1
isdn switch-type basic-net3 (1)
!
interface Ethernet0
ip address 10.0.0.1 255.255.255.0
ip nat inside (2)
!
interface bri 0
ip address negotiated (3)
ip nat outside
encapsulation PPP
PPP authentication pap callin (4)
PPP multlink (5)
dialer-group 1
dialer string 2633
PPP pap sent-username 263 password 263 (6)
ip route 0.0.0.0 0.0.0.0 bri 0
access-list 2 permit any (7)
dialer-list 1 protocol ip permit (8)
ip nat inside source list 2 interface bri 0 overload (9)
……
End

行车速度大于（）的线路，不宜采用明桥面刚桥。

A.120km/h

B.160km/h

C.200km/h

D.250km/h