单项选择题
A.1~2B.5~8C.8~10D.10~12
A.1~2B.6~8C.3~5D.8~10
A.50~30Hz ;0.2~0.4mmB.50~30Hz ;0.6~0.8mmC.80~100Hz ;0.2~0.4mmD.80~100Hz ;0.6~0.8mm