latex中的三种字体格式

\documentclass{
     article}
\usepackage{
     ctex}
\begin{
     document}
\noindent Fashion norms have changed greatly between decades.\\
大家好\\
\rmfamily
Fashion norms have changed greatly between decades.\\
\sffamily
Fashion norms have changed greatly between decades.\\
\ttfamily
Fashion norms have changed greatly between decades.\\
\ttfamily\small
Fashion norms have changed greatly between decades.\\
\ttfamily\large
Fashion norms have changed greatly between decades.\\
\end{
     document}