A:hadn’t
B:wasn’t
C:wouldn’t
D:could
电池
电解池
A
H+移向Pb电极
B
每消耗3molPb
生成2molAl2O3
C
正极:PbO2+4H++2e﹣=Pb2++2H2O
阳极:2Al+3H2O﹣6e﹣=Al2O3+6H+
D
提示问题:
1) How often do you exercise?
2) What's your favourite sport? Why?
3) When do you do sports?