请问如何排版子图片中的子图？

代码如下：

\documentclass{article}
\usepackage{subfig}
\usepackage{graphicx}

\begin{document}
\begin{figure}
\centering
  \subfloat[caption fig (a).]{\parbox{\textwidth}{\centering\includegraphics[width=2cm]{example-image-a}\hskip1cm\includegraphics[width=2cm]{example-image-a}\\
\includegraphics[width=2cm]{example-image-a}\hskip1cm\includegraphics[width=2cm]{example-image-a}\hskip1cm\includegraphics[width=2cm]{example-image-a}}}

 \subfloat[caption fig (b).]{\parbox{\textwidth}{\centering\includegraphics[width=2cm]{example-image-a}\hskip1cm\includegraphics[width=2cm]{example-image-a}\\
\includegraphics[width=2cm]{example-image-a}\hskip1cm\includegraphics[width=2cm]{example-image-a}\hskip1cm\includegraphics[width=2cm]{example-image-a}}}

   \caption{caption fig.}\label{fig:}
\end{figure}
\end{document}

效果图如下：

我喜欢简单直接。我不喜欢 subfig、subfigure，我喜欢 subcaption。

\documentclass{ctexart}
\usepackage{subcaption,graphicx}
\begin{document}
\begin{figure}
\begin{subfigure}{\linewidth}
\mbox{}\hfill%
\includegraphics[width=0.3\linewidth]{example-image-a.pdf}\hfill
\includegraphics[width=0.3\linewidth]{example-image-b.pdf}\hfill
\mbox{}\\[5mm]
\includegraphics[width=0.3\linewidth]{example-image-a.pdf}\hfill
\includegraphics[width=0.3\linewidth]{example-image-b.pdf}\hfill
\includegraphics[width=0.3\linewidth]{example-image-c.pdf}
\caption{子图1}
\end{subfigure}
\begin{subfigure}{\linewidth}
\mbox{}\hfill%
\includegraphics[width=0.3\linewidth]{example-image-a.pdf}\hfill
\includegraphics[width=0.3\linewidth]{example-image-b.pdf}\hfill
\mbox{}\\[5mm]
\includegraphics[width=0.3\linewidth]{example-image-a.pdf}\hfill
\includegraphics[width=0.3\linewidth]{example-image-b.pdf}\hfill
\includegraphics[width=0.3\linewidth]{example-image-c.pdf}
\caption{子图2}
\end{subfigure}
\caption{图示}
\end{figure}
\end{document}

效果：