How to align text without two column?

Question

I want to have the following text alignment and I don't wanna use any "two column" and table because a environment i use doesn't support them. :( The text format looks like below picutre. Basicly i want to split a line from middle, and for a line text there will be 2 parts, and 1st part is in left and 2nd part is in right. however, there are some lines which have long text and i don't want to split them to two part, thus they will not split. Thanks a lot for help!

Answer 1

You can define a command that manually puts its first argument into the "left column" and the second argument into the "right column.

\documentclass{article}
\newcommand*\leftright[2]{%
  \leavevmode
  \rlap{#1}%
  \hspace{0.5\linewidth}%
  #2}
\begin{document}
\leftright{first line part 1}{first line part 2} \par
A longer line that isn't split in two columns \par
\leftright{third line part 1}{third line part 2}
\end{document}