如果正文中的章节标题是大写，我该如何将其格式化为小写？我尝试使用 titletoc 和 tocloft，但找不到正确的代码。Tgis 是我的序言。
\setcounter{chapter}{33}
\usepackage[pagestyles]{titlesec}
\usepackage{ifthen}
\usepackage{array}
\usepackage[draft]{graphicx}
\graphicspath{{G:/LyX/Moreu_Tomo_II/Figuras/}}
\usepackage{rotating}
\usepackage{lscape}
\usepackage{longtable}
\usepackage{fnpos}
\usepackage{booktabs}
\usepackage{dcolumn}
\usepackage{slashbox}
\usepackage{pict2e}
\usepackage{multirow}
\usepackage{float}
\floatplacement{table}{tp}
\usepackage{morefloats}
\usepackage{flafter}
\usepackage{floatflt}
\usepackage{colortbl}
\usepackage{wrapfig}
\usepackage{enumitem}
\usepackage{nccparskip}
\usepackage{eso-pic,everyshi,calc}
\usepackage{dashrule}
\usepackage{marvosym}
\usepackage{amsbsy}
\usepackage{yhmath}
\usepackage{txfonts}
\usepackage{textcomp}
\usepackage{mathcomp}
\usepackage{gensymb}
\usepackage[e]{esvect}
\usepackage[spanish,es-nodecimaldot,es-tabla]{babel}
\usepackage{ccaption}
\usepackage[labelsep=endash,font={small,it},labelformat=simple,labelfont=bf,figurewithin=none,justification=justified]{caption}
\usepackage{nowidow}
\usepackage{subcaption}
\usepackage{pifont}
\usepackage{arcs}
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage{upgreek}
\renewcommand{\thechapter}{\Roman{chapter}}
\renewcommand{\thesection}{\ifnum\value{section}<10 \arabic{chapter}0\arabic{section}\else\arabic{chapter}\arabic{section}\fi}
\renewcommand{\lg}{\log \nolimits}
\renewcommand{\theequation}{\arabic{chapter}.\arabic{equation}}
\renewcommand{\thetable}{\arabic{table}}
\newcommand{\sen}{\operatorname{\sen}}
\newcommand{\tg}{\operatorname{\tg}}
\newcommand{\cotg}{\operatorname{\cot}}
\newcommand{\cosec}{\operatorname{\csc}}
\addto\captionsspanish{\renewcommand{\figurename}{Fig.}}
\addto\captionsspanish{\renewcommand{\tablename}{Tabla}}
\DeclareMathOperator{\gs}{\textrm{\!\textdegree}}
\DeclareCaptionLabelFormat{tabla}{#2}
\titleformat{\chapter}[display]
{\Large\bfseries\fillast\vspace{-25pt}}
{\normalfont\bfseries\chaptername\hspace{5pt}\thechapter}
{.5ex minus .1ex}
{\large}[\vspace{-15pt}]
\titleformat{\section}[runin]
{\normalfont\bfseries}
{\thesection.}{.5em}{}[.---\:]
\titlespacing{\section}
{\parindent}{1.5ex plus .1ex minus .2ex}{0pt}
\makeatletter
\def\cleardoublepage{\clearpage\if@twoside \ifodd\c@page\else
\vspace*{\fill}
\thispagestyle{empty}
\newpage
\if@twocolumn\hbox{}\newpage\fi\fi\fi}
\def\dotfill#1{\cleaders\hbox to #1{.}\hfill}
\newcommand\dotline[2][.5em]{\leavevmode\hbox to #2{\dotfill{#1}\hfil}}
\makeatother
\setlist{noitemsep}
\setitemize{listparindent=\parindent,labelindent=\parindent,leftmargin=*,labelsep=1em}
\setlist[enumerate]{listparindent=\parindent,labelsep=*,leftmargin=1.5pc}
\setlist[enumerate,1]{label=\bf\arabic*.,ref=\bf\arabic*.}
\setlist[enumerate,2]{label=\bf{\alph*}),ref=\bf{\alph*})}
\setlist[enumerate,3]{label=\roman*),ref=\roman*)}
\usepackage[bookmarks=true,bookmarksopen=true,bookmarksopenlevel=2,bookmarksnumbered=true]{hyperref}
\usepackage{bookmark}
\renewcommand{\frac}[2]{\genfrac{}{}{0.1pt}{}{#1}{#2}}
\renewcommand{\dfrac}[2]{\genfrac{}{}{0.1pt}{}{#1}{#2}}
\renewcommand{\cfrac}[2]{\genfrac{}{}{0.1pt}{}{#1}{#2}}
\renewcommand{\tfrac}[2]{\genfrac{}{}{0.1pt}{}{#1}{#2}}
\setlength\fboxrule{.1pt}
感谢您的关注。