\documentstyle[12pt]{article}
\begin{document}
\begin{flushleft}
In another moment down went Alice after it,
never once considering how in the world she
was to get out again.
The rabbit-hole went straight on like a tunnel
for some way, and then dipped suddenly down,
so suddenly that Alice had not a moment to
think about stopping herself before she found
herself falling down a very deep well.
\end{flushleft}
\end{document}
Another way to do this is to use the declaration. Notice that the
\raggedright declaration is in effect as long
as the environment it is in is in effect. Ragged right justification
will be turned off as soon as it encounters a
\end{ } command.
\documentstyle[12pt]{article}
\begin{document}
\raggedright
In another moment down went Alice after it,
never once considering how in the world she
was to get out again.
The rabbit-hole went straight on like a tunnel
for some way, and then dipped suddenly down,
so suddenly that Alice had not a moment to
think about stopping herself before she found
herself falling down a very deep well.
\end{document}