桥墩轻型化的途径是将重力式桥墩改为（），以达到减轻重量，节省圬工的目的。

A. 驶回基站
B. 驶回首站
C. 驶回底站
D. 就近楼层停止运行

An access point will search for a controller using a broadcast address if using LWAPP Layer 2 and a unicast address if using LWAPP Layer 3 mode.
B. If multiple wireless controllers are detected by an access point， the controller with the fewest associated access points is chosen to associate with.
C. In order to associate in Layer 3 mode， the access point must have been preconfigured with an IP address.
D. Once an access point associates with a controller in LWAPP Layer 3 mode， it receives an IP address from the controller.
E. An access point first searches for a controller in LWAPP Layer 2 mode. If the search is not successful， the access point then attempts to locate a controller in LWAPP Layer 3 mode.
F. If multiple wireless controllers are detected by an access point， all of them will be used and traffic will be load balanced.

A. 正确
B. 错误