干扰余量＝lg（），50％的系统负载对应（）dB的干扰余量。
参考答案：（1/（1-小区负载））；3
Nowadays more people are advised to arrange for insurance ______ they need medical care. [ ]
A. in order
B. in need
C. in case
D. in hope
闭塞分区编号用（）该闭塞分区的通过信号机的编号来编号。
