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## 编译环境
操作系统
* [x ] Windows 7/8/10
* [ ] macOS
* [ ] Linux
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Tex发行版
* [x ] TexLive `2020`
* [ ] MikTeX `版本号`
* [ ] CTeX
`若需勾选，请把[ ]改成[x]`
## 我的问题
Runaway argument?
{\LaTeX {}公式输入｝ \par \author {China\TeX ｛｝在线培训课\ETC.
! File ended while scanning use of \title .
\par
<*> 2-1-eq-1.tex
原代码：
\documentclass[b5paper]{ctexbook}
\usepackage[margin=2cm]{geometry}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{mathrsfs}
\usepackage{bm}
\numberwithin{equation}{section}
\begin{document}
\title{\LaTeX {}公式输入｝
\author{China\TeX｛｝在线培训课程\\ Jamesfang}
\maketitle
\tableofcontents
\fontsize{14pt}{\baselineskip}\selectfont
\mainmatter
\chapter{简介}
\section{概述}
The quick brown fox jumps over$\frac{-b\pm \sqrt{b^2-4ac}} {2a}$ the lazy dog.
The quick brown fox jumps over $$\frac{-b\pm \sqrt{b^2-4ac}} {2a}$$the lazy dog.
The quick brown fox jumps over\[a^2+b^2=c^2\] the lazy dog.The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog.
\end{document}
