A.10,0.1~0.2% B.12,0.1~0.2% C.10,0.2~0.3% D.12,0.2~0.3%
A.低、高 B.高、低 C.高、高 D.低、低
A.空氣 B.氧氣 C.天燃?xì)?br /> D.煤氣