A:点①所示溶液中:c(H+)+c(H2C2O4)+c(HC2O4﹣)=c(OH﹣)
B:点②所示溶液中:c(HC2O4﹣)+2c(C2O42﹣)=c(Na+)+c(H+)
C:点③所示溶液中:c(Na+)>c(HC2O4﹣)>c(H2C2O4)>c(C2O42﹣)
D:滴定过程中可能出现:c(Na+)>c(C2O42﹣)=c(HC2O4﹣)>c(H+)>c(OH﹣)
3元6角=____角
7元5角=____角
男女同学之间的友谊应该在集体活动中发展。( )
78-4x=58
x=____