在X+2O2CO2+2H2O中,根据质量守恒定律,X的化学式为( )
A:CH4
B:C2H5OH
C:CH3OH
D:CH3COOH
(____)A. This is the leg.
(____)B. Let's go to school.
(____)C. Shake your body.
(____)D. This is my face.
(____)E. Touch your nose.
函数y=x-2中,自变量x的取值范围是( )