A:FeBr2溶液中通人少量Cl2:2Fe2++Cl2=2Fe3++2Cl-
B:将氧气通入酸性碘化钾溶液中:2I-+O2+4H+=I2+2H2O
C:硫代硫酸钠溶液中加入稀硫酸:2H++S2O32-=S↓+SO2↑+H,O
D:酸性高锰酸钾溶液中加入草酸:2MnQ4-+5H2C2O4+6H+=2Mn2++10CO2↑+8H2O
What made the children ____ (laugh) loudly?
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