OMU单板指标以下哪项是必需检查项（）。
A.光通道间隔
B.插入损耗
C.接收灵敏度
D.中心频率
参考答案：B
Betty had nothing for breakfast, ____________? [ ]
A. hadn't she
B. had she
C. didn't she
D. did she
简述利率变化对储蓄有何影响？
