如何在求职信中写数学？

Question

我无法$\ell_1$在这封求职信中写和其他数学符号：需要什么包？

\documentclass[a4paper,parskip=full,]{scrlttr2}
\usepackage[urw-garamond]{mathdesign}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{fontspec}
%\setmainfont{GaramondNo8}
%\setlength{\parindent}{0pt}
\usepackage{xcolor}
\usepackage[english]{babel}
\nonfrenchspacing

%\setkomavar{fromname}{Ole Nordmann}
%\setkomavar{fromaddress}{Storebakken 15 \\ 5500 Haugesund}
%\setkomavar{fromphone}{[phone]}
\makeatletter


\renewcommand*{\raggedsignature}{\raggedright}

\makeatother
\begin{document}

\begin{letter}{H.P. \\ K. N.  Technology
Tehran, I. R. Iran
 \\ Email Add.:}
\\ Tel: : }

%\KOMAoptions{fromphone=true,fromfax=false}
\setkomavar{subject}{COVER LETTER FOR SUBMISSION OF MANUSCRIPT}
%\setkomavar{date}
\opening{Dear Dear Editor,}




\closing{Sincerely}
%\encl{loan application, gift certificate for chocolate}

\begin{itemize}
\item[No.] 1:\\
\begin{tabular}{|l|r@{~}|c|@{~}l@{\qquad}|r|}
\hline
    %& Column 1& Column 2\\\hline
Ful name& [email protected]  \\\hline
Institution  & ...\\\hline
Country & \\\hline
E-mail Address  & \\\hline
\end{tabular}
\end{itemize}
\begin{itemize}
\item[No.] 2:\\
\begin{tabular}{|l|r@{~}|c|@{~}l@{\qquad}|r|}
\hline
    %& Column 1& Column 2\\\hline
Ful name& ... \\\hline
Institution  & ...\\\hline
Country & \\\hline
E-mail Address  & \\\hline
\end{tabular}
\end{itemize}
\begin{itemize}
\item[No.] 3:\\
\begin{tabular}{|l|r@{~}|c|@{~}l@{\qquad}|r|}
\hline
    %& Column 1& Column 2\\\hline
Ful name& ... \\\hline
Institution  & ...\\\hline
Country & \\\hline
E-mail Address  & \\\hline
\end{tabular}
\end{itemize}
\begin{itemize}
\item[No.]4:\\
\begin{tabular}{|l|r@{~}|c|@{~}l@{\qquad}|r|}
\hline
    %& Column 1& Column 2\\\hline
Ful name& ... \\\hline
Institution  & ...\\\hline
Country & \\\hline
E-mail Address  & \\\hline
\end{tabular}
\end{itemize}
\end{letter}
\end{document}

Answer 1

我看不出为什么使用$math$或输入数学运算\(math\)会失败 - 但我确实看到了代码中似乎存在错误：

\begin{letter}{H.P. \\ K. N.  Technology
Tehran, I. R. Iran
 \\ Email Add.:}
\\ Tel: : }

}后面多了一个\\ Email Add.:，也就是说，这个块应该是：

\begin{letter}{H.P. \\ K. N.  Technology
Tehran, I. R. Iran
\\ Email Add.:
\\ Tel: : }