标况下,10g CO和CO2的混和气体的体积为6.72L,则此混和气体中CO和CO2的物质的量之比是[ ]
A.1:1
B.2:1
C.4:3
D.1:2
答案:B
Who do you think is the right person to ______the task?
A.undergo
B.undertake
C.understand
D.underline
恒无功功率调节