单项选择题
A.20B.50C.50~100D.100
A.1/(10Vmax)B.1/(9Vmax)C.1/(8Vmax)D.1/(7Vmax)
A.2B.3C.4D.5
A.-∞~+20B.-20℃~+15℃C.-10℃~+15℃D.-15℃~+10℃
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