A.需求閥打開,呼氣閥關(guān)閉 B.需求閥打開,呼氣閥打開 C.需求閥關(guān)閉,呼氣閥關(guān)閉 D.需求閥關(guān)閉,呼氣閥打開
A.30ppmB.15mg/m3(10ppm)C.30mg/m3(20ppm)D.150mg/m3(100ppm)
A.柴油 B.清潔的水 C.堿水 D.汽油