如图是甲醇——空气电池工作时的示意图。甲醇在催化剂作用下提供质子(H+) 和电子, 电子经外电路、质子经内电路到达另一极与氧气反应。下列说法中正确的是( ) A.正极反应式为:2H+ +2e— =H2↑ B.乙电极为电池的负极,b处通入的物质是空气 C.负极反应式为:CH3OH+H2O-6e—=CO2+6H+ D.在电池反应中,每消耗l mol氧气,理论上能生成标准状况下CO2气体22.4L2.--I got up at 6this morning.I thought it was Friday.--You _____ so early.It is Sunday today; you don't have to go to work.( )A.mustn't have got upB.needn't have got upC.needn't get upD.mustn't get up