不需要的空白页，以及在各节之间重置图表计数

Question

抱歉，我一次问了两个问题，但是我在使用以下代码时遇到了麻烦，它在各个部分之间产生了不需要的空白页，我不知道为什么。

而且我也尝试过使用 \page*{} 来重置图表计数器，但无济于事，我是不是做了什么愚蠢的事情？

\documentclass{book}

\usepackage{blindtext}
\usepackage{tikz}
\usepackage{tkz-euclide}


\newcommand{\AG}{1.5}


% Standard packages
\usepackage{
    float, 
    graphicx
}

% Set page margins
\usepackage[top=1.0in, bottom=1.0in, left=1.0in, right=1.0in]{geometry}

\setlength{\marginparwidth}{0pt}

% Set nice page headers
\usepackage{fancyhdr}
\pagestyle{fancy}

% Paragraph style
\setlength{\parindent}{0em}
\setlength{\parskip}{1em}


% Proposition environment
\newenvironment{explanation}
    {\begin{center}\em}
    {\end{center}}

 \newcounter{CountStep}

\newcounter{CountDiag}
\newenvironment{diagram}
{\stepcounter{CountStep}\stepcounter{CountDiag}\vspace*{10pt}     Step~\theCountStep\par
\begin{center}
\begin{tikzpicture}}
        {\end{tikzpicture}\vspace*{-5pt}\par Diagram~\theCountDiag
    \end{center}}
 
 
\setcounter{chapter}{1}

\usepackage{titlesec}

\titleformat{\chapter}[display]
{\normalfont\huge\bfseries}{}{0pt}{\Huge}
\titlespacing*{\chapter}
{0pt}{0pt}{30pt}

\titleformat{\section}[display]
{\normalfont\huge\bfseries}{}{-20pt}{\Large}
\titlespacing*{\section}
{0pt}{0pt}{10pt}

\begin{document}
\part*{}
\section{Opposite angles}

\begin{explanation}
 When two straight lines intersect (or cross), two pairs of opposite angles are formed. Opposite angles are equal.
\end{explanation}

\begin{center}
\begin{tabular}{cc}
\begin{tikzpicture}
   \tkzDefPoint(-2,1){A}
   \tkzDefPoint(3,-2){B}
   \tkzDefPoint(2.5,1.5){C}
   \tkzDefPoint(-2,-2.2){D}

       \tkzDrawSegment(A,B)
       \tkzDrawSegment(C,D)
    
           \tkzInterLL(A,B)(C,D) \tkzGetPoint{E}
        
           \tkzLabelPoints[above](A,B)
           \tkzLabelPoints[below](C,D)
 \end{tikzpicture}
&
\begin{tikzpicture}
\tkzDefPoint(-2,1){A}
\tkzDefPoint(3,-2){B}
\tkzDefPoint(2.5,1.5){C}
\tkzDefPoint(-2,-2.2){D}

    \tkzDrawSegment(A,B)
    \tkzDrawSegment(C,D)
    
        \tkzInterLL(A,B)(C,D) \tkzGetPoint{E}
        
        \tkzLabelPoints[above](A,B)
        \tkzLabelPoints[below](C,D)
 \end{tikzpicture}
\end{tabular}
\end{center}

\clearpage

\part*{}
\section{Alternate Angles}

\begin{explanation}
When a straight line crosses two parallel lines (shown by the arrow heads on the lines), it forms two pairs of alternate angles (in a sort of a $Z$ shape).  Alternate angles are equal.
\end{explanation}

\begin{diagram}

\tkzDefPoint(0,0){A}
\tkzDefPoint(4,0){B}
\tkzDefPoint(0,3){C}
\tkzDefPoint(4,3){D}
\tkzDrawSegment(A,B)
\tkzDrawSegment(C,D)

\end{diagram}

\clearpage

\part*{}
\section{Corresponding angles}

\begin{explanation}
Corresponding angles formed by parallel lines are equal. Corresponding angles form a sort of $F$-shape.
\end{explanation}

\begin{diagram}

\tkzDefPoint(0,0){A}
\tkzDefPoint(4,0){B}
\tkzDefPoint(0,3){C}
\tkzDefPoint(4,3){D}
\tkzDrawSegment(A,B)
\tkzDrawSegment(C,D)

\end{diagram}

\clearpage

\part*{}
\section{Co-interior angles}

\begin{explanation}
When a straight line crosses two parallel lines to make a kind of $C$-shape, the co-interior angles (allied angles) total $180/^{circ}$.
\end{explanation}

\begin{diagram}

\tkzDefPoint(0,0){A}
\tkzDefPoint(4,0){B}
\tkzDefPoint(0,3){C}
\tkzDefPoint(4,3){D}
\tkzDrawSegment(A,B)
\tkzDrawSegment(C,D)

\end{diagram}

\clearpage

\end{document}

欢迎任何帮助或指点，谢谢。