答案1
请注意,在这个网站上,我们并不完全喜欢帮我做问题。不过,我正在午休……
\documentclass{article}
\usepackage{tikz,amsmath}
\begin{document}
\begin{tikzpicture}
\foreach\x in {30,150,270} {%
\node[draw,circle,minimum size=1cm,text=blue,font=\Large] at (\x:1) {$\boldsymbol+$};
\draw[blue,very thin](\x:1)--(0,0);
}
\foreach\x in {90,210,330} {%
\node[draw,circle,minimum size=1cm,text=red,font=\Large] at (\x:1) {$\boldsymbol-$};
\draw[red,very thin](\x:1)--(0,0);
}
\end{tikzpicture}
\end{document}