答案1
这是一个解决方案。
\documentclass{book}
\makeatletter
\def\@part[#1]#2{%
\ifnum \c@secnumdepth >-2\relax
\refstepcounter{part}%
\addcontentsline{toc}{part}{\thepart\hspace{1em}#1}%
\else
\addcontentsline{toc}{part}{#1}%
\fi
\markboth{}{}%
{\centering
\interlinepenalty \@M
\normalfont
\ifnum \c@secnumdepth >-2\relax
\huge\bfseries \partname\nobreakspace\thepart
\par
\vskip 20\p@
\fi
\Huge \bfseries #2\par}%
\vfil\newpage\thispagestyle{plain} % or empty
\null\vfil
{\centering
\interlinepenalty \@M
\normalfont
\huge\bfseries \partname\nobreakspace\thepart
\par
\vskip 20\p@
\Huge \bfseries #2\par}%
\vfil\newpage}
% next is for starred part if there is
\def\@spart#1{%
{\centering
\interlinepenalty \@M
\normalfont
\Huge \bfseries #1\par}%
\vfil\newpage\thispagestyle{plain} % or empty
\null\vfil
{\centering
\interlinepenalty \@M
\normalfont
\Huge \bfseries #1\par}%
\vfil\newpage}
\makeatother
\begin{document}
\tableofcontents
bla bla
\part{this is the first part}
some bla bla
\end{document}