区分O2、H2、CO2三种气体的最简便的方法是( )
A:将气体通入澄清石灰水
B:将气体通过红热的铜网
C:将气体通过灼热的氧化铜
D:用燃着的木条伸入集气瓶中
After the clothes were dry outside, she them and put them in her suitcase.
已知f(x)为R上的可导函数,且∀x∈R,均有f(x)>f'(x),则有( )
—Nobody. I learned it by