在终端输入
sudo gedit /etc/fonts/conf.d/69-language-selector-zh-cn.conf
修改69-language-selector-zh-cn.conf文件如下：
<fontconfig>
<match target="pattern">
<test qual="any" name="family">
<string>serif</string>
</test>
<edit name="family" mode="prepend" binding="strong">
<string>DejaVu Serif</string>
<string>AR PL UMing CN</string>
<string>AR PL UKai CN</string>
<string>AR PL ZenKai Uni</string>
<string>AR PL ShanHeiSun Uni</string>
<string>Bitstream Vera Serif</string>
<string>WenQuanYi Bitmap Song</string>
</edit>
</match>
<match target="pattern">
<test qual="any" name="family">
<string>sans-serif</string>
</test>
<edit name="family" mode="prepend" binding="strong">
<string>WenQuanYi Bitmap Song</string>
<string>AR PL UMing CN</string>
<string>AR PL UKai CN</string>
<string>AR PL ZenKai Uni</string>
<string>WenQuanYi Zen Hei</string>
<string>Bitstream Vera Sans</string>
<string>AR PL ShanHeiSun Uni</string>
<string>DejaVu Sans</string>
</edit>
</match>
<match target="pattern">
<test qual="any" name="family">
<string>monospace</string>
</test>
<edit name="family" mode="prepend" binding="strong">
<string>DejaVu Sans Mono</string>
<string>Bitstream Vera Sans Mono</string>
<string>WenQuanYi Bitmap Song</string>
<string>AR PL UMing CN</string>
<string>AR PL UKai CN</string>
<string>AR PL ZenKai Uni</string>
<string>WenQuanYi Zen Hei</string>
<string>AR PL ShanHeiSun Uni</string>
</edit>
</match>
</fontconfig>
一定要做完第二步，不然还是会出现方框的问题，
把第二个大项中的第一项改成WenQuanYi Bitmap Song
我的机子上是改成是WenQuanYi Micro Hei，这样就行拉，谢谢原作者提供的这么好的方法。