蒸发器液位控制指标为（）%

A.6.5-21m³/h
B.6.5-20.0m³/h
C.5-20.0m³/h
D.6.7-20.0m³/h

A.＜4ppm
B.＜3ppm
C.＜2ppm
D.＜5ppm

A.＜30ppm
B.＜35ppm
C.＜20ppm
D.＜25ppm