punctuation in traditional Chinese {bkai} is in the middle instead of the right bottom corner, how to fix it?

Question

I use the following code for some traditional Chinese characters output:

\documentclass[12pt]{article}
\usepackage{CJK}
\begin{document}
\begin{CJK}{UTF8}{bkai}
君子一言，駟馬難追。
\end{CJK}
\end{document}

The out put is

I know this is the default setting of bkai maybe (I also saw it from here), but how can I make the punctuation lie at the right bottom corner?