调度通信数字设备用户两线接口电平（）
A.发-4收-4dBr
B.发0收-3.5dBr
C.发0收-4dBr
D.发-4收-7dBr
参考答案：B
After problems are posed, we should sort them out, ______ the advantages and disadvantages and decide what to do.
A．weigh
B．think
C．range
D．examine
