A:CH4+Cl2﹣→CH3Cl+HCl
B:CH2═CH2+Br2﹣→CH2BrCH2Br
C:nCH2═CH2﹣→
D:CH3CH2OH+CH3COOH﹣→CH3COOCH2CH3+H2O
下图漫画《经验》(作者:何青云)给我们的启示是( )