下列反应中,属于取代反应的是
①CH3CH2OH 浓H2SO4
△CH2=CH2↑+H2O
②C6H6+HNO3浓H2SO4
△C6H5NO2+H2O
③CH3CH2COOH+CH3CH2OH浓H2SO4
△ CH3CH2COOCH2CH3+H2O
④CH3CH=CH2+Br2ccl
CH3CHBrCH2Br()
A.①②
B.①③
C.②③
D.②④