用p或者m可以控制每列的寬度（需載入array宏包）。
要整個表格相對於頁面居中，用chngpage宏包的adjustwidth,如下：
\documentclass[oneside]{article}
\usepackage{chngpage}
\usepackage{array}
\begin{document}
\begin{adjustwidth}{-1cm}{-1cm}
\begin{tabular}{|p{.2\textwidth}| p{.2\textwidth}| m{.7\textwidth}|}
\hline
new & old & all boring, all boring, all boring, all boring, all boring, all boring, all boring, all boring, all boring, all boring, all boring, all boring, all boring, all boring, \\ \hline
\end{tabular}
\end{adjustwidth}
\end{document}