\documentclass[12pt]{scrartcl}

\usepackage[margin=2cm]{geometry}
\usepackage{multicol}
\usepackage{tabularx}
\usepackage{tcolorbox}
\usepackage[table]{xcolor}

\pagestyle{empty}
\renewcommand{\familydefault}{\sfdefault}
\rowcolors{1}{black!5!white}{white}

\begin{document}

\begin{center}
  {\large tableaux de conjugaison}\\
  \vskip1ex
  {\Huge \textbf{-er} (example: aim-er)}
\end{center}

\vskip1em

\begin{multicols}{2}

\begin{tcolorbox}[tabularx={l|X}, title={\textbf{présent}}]
  j’ & aim-e \\
  tu & aim-es \\
  elle/il & aim-e \\
  nous & aim-ons \\
  vous & aim-ez \\
  elles/ils & aim-ent \\
\end{tcolorbox}

\end{multicols}

\end{document}


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