A.第8行代码: celsius = 5.0 / 9 * (fahr - 32)第10行代码: fahr = fahr + step
B.第8行代码: celsius = 5.0 / (9 * (fahr - 32))第10行代码: fahr = fahr + step
C.第8行代码: celsius = 5.0 / 9 * (fahr - 32)第10行代码: fahr = fahr - step
D.第8行代码: celsius = 5 / 9 * (fahr - 32)第10行代码: fahr = fahr + step
A.0.1%CH4,0.1%CH4
B.0.1%CH4,0.4%CH4
C.0.01%CH4,0.1%CH4
D.0.01%CH4,0.01%CH4