A:O2→2O
B:H2+Cl2→2HCl
C:Na2O+H2O='2NaOH'
D:2Cl→Cl2
Don't forget to ____ ____ others when you do something wrong.
现在如图所示三套硬质试管可供选择:(固定装置铁架台和热源酒精灯已省略):