将表格单元格内容置于标题/副标题下方

Question

我怎样才能将cell1、cell4和放置在列cell7下方particle以及cell2、cell5和放置在列cell8下方？massfamily 1

    \documentclass[11pt,a4paper]{article}
    \usepackage{blindtext}
    \usepackage{mathtools}
    \DeclareMathOperator{\sgn}{sgn}
\begin{document}
\begin{center}
\begin{tabular}{c c c}
Family 1 & Family 2 & Family 3\\
Particle \hspace{2em} Mass & Particle \hspace{2em} Mass & Particle \hspace{2em} Mass\\
\hline
cell1 & cell2 & cell3 \\
\hline
cell4 & cell5 & cell6 \\  
\hline
cell7 & cell8 & cell9 \\
\hline
\end{tabular}
\end{center}
\end{document}

Answer 1

定义 6 列并更改\tabcolsep为1em

\documentclass[11pt,a4paper]{article}
\usepackage{blindtext}
\usepackage{mathtools}
\DeclareMathOperator{\sgn}{sgn}
\begin{document}
\begin{center}
\setlength{\tabcolsep}{1em}
\begin{tabular}{*{6}{c}}
Family 1 & Family 2 & Family 3\\
Particle & Mass & Particle & Mass & Particle & Mass\\
\hline
cell1 & & cell2 & & cell3 \\
\hline
cell4 && cell5 && cell6 \\
\hline
cell7 && cell8 && cell9 \\
\hline
\end{tabular}
\end{center}
\end{document}