[Tex/LaTex] How to insert a paragraph before the chapter title

chapterssectioningtitlesec

I need to include several lines before the chapter title for some (not all) chapters. A new chapter always starts with a new page, how to realize the following layout for certain chapter while other chapters are normal?

                              header
-------------------------------------------------------------------
paragraph before the chapter title


Chapter 1 Introduction

   xxxxxxxxxxxxxxxxxxxxxxxxxxx

-------------------------------------------------------------------
                              footer

Best Answer

You can temporarily switch off the impact of a \clearpage - typically inserted when using \chapter:

enter image description here

\documentclass{report}
\usepackage{lipsum}
\begin{document}
\chapter{A chapter}
\lipsum[1]

{
\cleardoublepage% Move to first page of new chapter
\let\clearpage\relax% Don't allow page break
\noindent\lipsum[2]

\chapter{Another chapter}
}
\lipsum[1]

\chapter{Final chapter}
\lipsum[1]
\end{document}

The above example would work in twoside mode as well.