错误:
H2SO4 %2B K2Cr2O7 %2B CH3CH2COH %3D H2O %2B K2SO4 %2B Cr2%28SO4%293 %2B CH3CH3COOH
^
不需要的字符 ('%')H2SO4 %2B K2Cr2O7 %2B CH3CH2COH %3D H2O %2B K2SO4 %2B Cr2%28SO4%293 %2B CH3CH3COOH
^
不需要的字符 ('%')