A:液氮作制冷剂
B:乙炔与氧气形成高温氧炔焰
C:酒精洗掉沾在试管璧上的碘
D:洗洁精通过乳化作用除去油污
下列关于世界人种与语言.宗教的说法中,正确的是( )
We will have to choose a person to __________ our class to take part in the competition.