单项选择题
A.7.5mg/m3 B.15mg/m3 C.30mg/m3 D.75mg/m3
A.1000mg/m3 B.750mg/m3 C.500mg/m3 D.150mg/m3
A.急性中毒 B.亚急性中毒 C.慢性中毒 D.职业中毒