Bobbie is always sick and weak       his brother Frank is a good football player, as strong as a horse.

A．when

B．as

C．while

D．though

AXCS的单板软件为1.15版本，如果该板有红灯一闪的告警指示，但是通过网管和命令行命令都查询不到告警，则故障可判断为（）。

A、外时钟输入丢失

B、未加载单板FPGA

C、扳手微动开关损坏

D、交叉连接错误