包含未编号的章节后，段落和目录中的字体大小和行距产生不良影响

Question

当我添加未编号的章节、摘要、致谢时，整个文档从目录到最后一章的字体大小和行距都随机变化。但是，如果我删除这些行，它的显示渲染就完美了。希望有人能帮忙。谢谢。

\documentclass[12pt,oneside]{book}%
\usepackage[a4paper,top=0.75in,bottom=0.75in,left=1.25in,right=1in]{geometry}
\usepackage[T1]{fontenc} 
\usepackage[utf8]{inputenc}
\linespread{1.3}
\begin{document}
\cleardoublepage %Clear any float page and new page start from right side
\pagenumbering{roman}

 \setcounter{secnumdepth}{2}%sections numbering upto 2
 %Unnumbered chapter start
\addcontentsline{toc}{chapter}{Abstract}%before  \listof...
\include{abstract}
\addcontentsline{toc}{chapter}{Acknowledgement}%before  \listof...
\include{acknowledgement}
 %Unnumbered chapter start

% Add table of content, figures,acronyms and symbols
\renewcommand{\contentsname}{Table of Contents}
\tableofcontents
\listoftables 
\listoffigures
\cleardoublepage %Clear any float page and new page start from right side
\pagenumbering{arabic}
\include{introduction}
\end{document}

当我包含未编号的章节时，输出是， 当我不包括章节时，输出是，