请问下图片的内容当文档类为ctexart时运行正常，改为beamer之后为啥就不行了

可以使用更加beamer-style的\againframe方法：

\documentclass[notheorems]{beamer}
\usepackage{tcolorbox}
\tcbuselibrary{skins,xparse}
\usepackage{tikz}
\usetikzlibrary{overlay-beamer-styles}

\makeatletter
\resetcounteronoverlays{tcb@cnt@exercise}
\NewTColorBox[auto counter,number within=section]{exercise}{+!O{}}{%
    enhanced,
    /tikz/alt=<1>{colframe=green!20!black}{colframe=red!20!black},
    colback=yellow!10!white,
    /tikz/alt=<1>{coltitle=green!40!black}{coltitle=red!40!black},
    fonttitle=\bfseries,
    underlay={
      \begin{tcbclipinterior}
        \shade[
          alt=<1>{inner color=green!80!yellow}{inner color=red!80!yellow},
          outer color=yellow!10!white
        ] (interior.north west) circle (2cm);
        \draw[help lines,step=5mm,yellow!80!black,shift={(interior.north west)}] (interior.south west) grid (interior.north east);
      \end{tcbclipinterior}
    },
    title={\alt<1>{Exercise~\thetcbcounter:}{Solution of Exercise~\thetcbcounter~on page \pageref{exercise@\thetcbcounter}:}},
    attach title to upper={\alt<1>{\label<1>{exercise@\thetcbcounter}\quad}{\label<2>{solution@\thetcbcounter}\par}},
    after upper={%
      \only<1>{%
        \par\hfill\textcolor{green!40!black}\itshape
        Solution on page~\pageref{solution@\thetcbcounter}
      }
    },
    #1
}
\makeatother

\begin{document}

\begin{frame}<1>[label=quack]%
    \begin{exercise}
      \begin{onlyenv}<1>
        Compute the derivative of the following function:
        \begin{equation*}
        f(x)=\sin((\sin x)^2)
        \end{equation*}
      \end{onlyenv}
      \begin{onlyenv}<2>
        The derivative is:
        \begin{align*}
        f'(x) &= \left( \sin((\sin x)^2) \right)'\\
        &=\cos((\sin x)^2) 2\sin x \cos x.
        \end{align*}
      \end{onlyenv}
    \end{exercise}
\end{frame}%

\againframe<2>{quack}

\end{document}