单项选择题
A.30% B.(26.5+3.5)/(100+6.5)×100% C.26.5% D.(26.5+3.5)/(100+6.5+3.5)×100%
A.CO2 B.SO2 C.CO2或SO2 D.CO2和SO2
A.30 B.60 C.90 D.120