单项选择题
A.55.5KHz;50-100μmB.55.5KHz;50-100nmC.55.5KHz;50-100cmD.55.5Hz;50-100nm
A.1m/sB.2m/sC.3m/sD.4m/sE.5m/s
A.23*23*15(cm)B.20*20*15(cm)C.23*23*18(cm)D.23*23*20(cm)E.20*20*18(cm)