表格-第一列标题未对齐

Question

在下表中，第一列的标题不知为何有点偏离。为什么会出现这种情况？我该如何进一步让其整体看起来更好？

\documentclass{article}
\usepackage{booktabs}

\begin{document}

\begin{table}[h]
\begin{tabular}{@{}ccccccc@{}}
\toprule
\multicolumn{2}{c}{\begin{tabular}[c]{@{}c@{}}Present\\State\end{tabular}} & \multicolumn{2}{c}{Input} & \multicolumn{2}{c}{\begin{tabular}[c]{@{}c@{}}Next\\ State\end{tabular}} & Output \\
\cmidrule(l){1-2} \cmidrule(lr){5-6} \cmidrule(lr){3-4} \cmidrule(l){7-7}
A          & B            & x & y        & A          & B          & z      \\ \midrule
0          & 0            & 0 & 0          & 0           & 0          & 0      \\
0          & 0            & 0 & 1          & 0           & 0          & 0      \\
0          & 0            & 1 & 0          & 1           & 1          & 0      \\
0          & 0            & 1 & 1          & 0           & 1          & 0      \\ [1ex]
0          & 1            & 0 & 0          & 0           & 0          & 0      \\
0          & 1            & 0 & 1          & 0           & 0          & 0      \\
0          & 1            & 1 & 0          & 1           & 0          & 0      \\
0          & 1            & 1 & 1          & 1           & 0          & 0      \\[1ex]
1          & 0            & 0 & 0          & 0           & 0          & 1      \\
1          & 0            & 0 & 1          & 0           & 0          & 1      \\
1          & 0            & 1 & 0          & 1           & 1          & 1      \\
1          & 0            & 1 & 1          & 0           & 1          & 1      \\[1ex]
1          & 1            & 0 & 0          & 0           & 0          & 1      \\
1          & 1            & 0 & 1          & 0           & 0          & 1      \\
1          & 1            & 1 & 0          & 1           & 1          & 1      \\
1          & 1            & 1 & 1          & 1           & 1          & 1      \\ \bottomrule
\end{tabular}
\end{table}
\end{document}

Answer 1

由于 \begin{tabular}{@{}ccccccc@{}}用作列说明符，因此必须使用

\multicolumn{2}{@{}c}{....

同样，即通过说删除第一列的水平空间@{}c。

\documentclass{article}
\usepackage{booktabs}

\begin{document}

\begin{table}[h]
\begin{tabular}{@{}ccccccc@{}}
\toprule
\multicolumn{2}{@{}c}{\begin{tabular}[c]{@{}c@{}}Present\\State\end{tabular}} & \multicolumn{2}{c}{Input} & \multicolumn{2}{c}{\begin{tabular}[c]{@{}c@{}}Next\\ State\end{tabular}} & Output \\
\cmidrule(r){1-2} \cmidrule(lr){5-6} \cmidrule(lr){3-4} \cmidrule(l){7-7}
A          & B            & x & y        & A          & B          & z      \\ \midrule
0          & 0            & 0 & 0          & 0           & 0          & 0      \\
0          & 0            & 0 & 1          & 0           & 0          & 0      \\
0          & 0            & 1 & 0          & 1           & 1          & 0      \\
0          & 0            & 1 & 1          & 0           & 1          & 0      \\ [1ex]
0          & 1            & 0 & 0          & 0           & 0          & 0      \\
0          & 1            & 0 & 1          & 0           & 0          & 0      \\
0          & 1            & 1 & 0          & 1           & 0          & 0      \\
0          & 1            & 1 & 1          & 1           & 0          & 0      \\[1ex]
1          & 0            & 0 & 0          & 0           & 0          & 1      \\
1          & 0            & 0 & 1          & 0           & 0          & 1      \\
1          & 0            & 1 & 0          & 1           & 1          & 1      \\
1          & 0            & 1 & 1          & 0           & 1          & 1      \\[1ex]
1          & 1            & 0 & 0          & 0           & 0          & 1      \\
1          & 1            & 0 & 1          & 0           & 0          & 1      \\
1          & 1            & 1 & 0          & 1           & 1          & 1      \\
1          & 1            & 1 & 1          & 1           & 1          & 1      \\ \bottomrule
\end{tabular}
\end{table}
\end{document}