如图所示,将铁棒和石墨棒擦入l L l mol·L-1食盐水中。下列说法正确的是 ( ) A.若电键K与N连接,铁被保护不会腐蚀 B.若电键K与N连接,正极反应式是 4OH-—4e-=2H2O+O2↑ C.若电键K与M连接,将石墨棒换成铜棒,可实现铁棒上镀铜 D.若电键K与M连接,当两极共产生28 L(标准状况)气体时,生成了1 mol NaOH
-May I go home now?-No, you ________.
[ ]
A.mustn't
B.can't
C.may
D.don't have to