单项选择题
A.上0%~10%下100%~90%B.上10%~40%下90%~60%C.上40%~60%下60%~40%D.上60%~90%下40%~10%
A.30B.50C.80D.95
A.荧光灯B.普通白炽灯C.低压钠灯D.高压汞灯