对付敌电子干扰，无线电通信设备可采用的方法有（）。
A.采用跳频通信
B.增大发射功率
C.采用无线电静默
D.尽量采用有线电通信
参考答案：A, B
Impressive ____, it fades next _____ the story of Armstrong's struggle against disease. [ ]
A. as is the record; by
B. as is the record; on
C. as the record is; for
D. as the record is; to
临界高血压是（）。
A．收缩压＜130mmHg和舒张压＜85 mmHg
B．收缩压140～159 mmHg或舒张压90～99 mmHg
C．收缩压160～179 mmHg或舒张压100～109 mmHg
D．收缩压140～149 mmHg或舒张压90～94 mmHg
E．收缩压≥140mmHg和舒张压＜90mmHg
