A:S+O2SO2
B:2KClO32KCl +3O2↑
C:Na2CO3+Ca(OH)2=CaCO3 ↓+2NaOH
D:C+2CuO2Cu+CO2↑
X=____
I'm a____ of tigers because I think they are too dangerous.
草原面积广阔的地区主要分布在( )