我有一个大学为论文写作提供的自定义文档类。一切都编译得很好，直到我添加了词汇表包。
! LaTeX Error: Command \dfrac already defined.
Or name \end... illegal, see p.192 of the manual.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.214 \newcommand{\dfrac}{\genfrac{}{}{}0}
结果是
amsmath.sty
214
LaTeX Error: Command \dfrac already defined.
Or name \end... illegal, see p.192 of the manual.
See the LaTeX manual or LaTeX Companion for explanation.
Type H <return> for immediate help.
...
l.214 \newcommand{\dfrac}{\genfrac{}{}{}0}
etoolbox.sty
Package etoolbox Warning: Patching '\end' failed! '\AfterEndEnvironment' will not work.
出现错误。我找不到任何解决方案，想知道是否有修复方法？