错误:
Fe2%28SO4%293 %2B H2O %3D Fe%28OH%293 %2B Fe %2B H2 %2B H2SO4 %2B O2
^不需要的字符 ('%')Fe2%28SO4%293 %2B H2O %3D Fe%28OH%293 %2B Fe %2B H2 %2B H2SO4 %2B O2
^不需要的字符 ('%')