（）和（）之比称为磁导率，用符号（）表示
参考答案：磁通密度B；磁场强度H；μ
— There were already five people in the car but they ____ to take me as well.
— It couldn't have been a pleasant journey. [ ]
A. tried
B. struggled
C. succeeded
D. managed
TD-LTE室内分布系统原则上可以采用特殊子帧配置为（）。
A、3：9：2
B、9：3：2
C、10：2：2
D、11：1：2
