A:1
B:2
C:3
D:4
94 =
10521 =
6913 =
8016 =
我是拼音小能手
____
潭面
镜未磨
白银盘
已知:Cr2O72- (橙色)+H2O ⇌ 2CrO42-(黄色)+2H+ △H= +13.8 kJ/mol,+6价铬盐在一定条件下可被还原为Cr3+,Cr3+在水溶液中为绿色。
Today is Sunday. Yesterday was ____ .