\documentclass[a4paper, 12pt]{article}
\textwidth 160mm
\title{Another Example}
\author{wwate shen}
\begin{document}
\maketitle

\newcommand{\tnss}{The not so Short Introdution to \LaTeX}
This is "\tnss" \ldots{} "\tnss".

\newcommand{\txsit}[1]
{This is the \emph{#1} Short Introdution to \TeX.}
%%
\begin{enumerate}
\item \txsit{not so}
\item \txsit{very}
\end{enumerate}

\newenvironment{king}{\begin{quote}}{\end{quote}}

\begin{king}
My humble subjects \ldots
\end{king}

{\small The small and
\textbf{bold} Romans ruled}
{\Large all of great big
\textit{Italy}.}

\flushleft
%\newenvironment{vardesc}[1]{\settowidth{\parindent}{#1:\} \makebox[Opt][r]{#1:\}}{}

\begin{displaymath}
a^2 + b^2 = c^2
\end{displaymath}

%\begin{vardesc}{Where}$a$,$b$ -- are adjust to the right
%angle of a right-angled triangle
%$c$ -- is the hypotenuse of the triangle and feels lonely.
%$d$ -- finally does not show up here at all.
%Isn't that puzzling
%\end{vardesc}

\makebox[\textwidth]{ c e n t e r a l}\par
\makebox[\textwidth][l]{ s p r e a d }\par
\framebox[1.1\width]{Guess I'm frame now!}\par
\framebox[1.1\width][c]{Bummer, i am too wide}\par
\framebox[1.1\width][c]{never mind, so am i}
\framebox[1.2\width][c]{Can you read this?}

\end{document}