Κώδικας: Επιλογή όλων
\documentclass[12pt, a4paper, twoside]{memoir}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{polyglossia}
\usepackage{xltxtra}
\usepackage{fontspec}
\setmainfont{GFS Didot}
\setdefaultlanguage{greek}
\usepackage[shortlabels]{enumitem}
\usepackage{showframe}
% new enumertion counter for true or false boxes
\newcounter{abc}
\renewcommand{\theabc}{\stepcounter{abc}\alph{abc}}
\newcommand{\answerbox}{\fbox{\phantom{M}}}
\begin{document}
\begin{enumerate}[label=\textbf{\arabic*.}, start=31]
\item Να χαρακτηριστούν οι παρακάτω προτάσεις ως σωστές ή λανθασμένες.
\setcounter{abc}{0}
\def\arraystretch{2}% increase vertical spacing
\noindent\begin{tabularx}{\textwidth}{cXcc}
& & Σ & Λ \\
(\theabc) & & \answerbox & \answerbox\\
(\theabc) & & \answerbox & \answerbox\\
(\theabc) & & \answerbox & \answerbox\\
(\theabc) & & \answerbox & \answerbox \\
(\theabc) & & \answerbox & \answerbox \\
(\theabc) & & \answerbox & \answerbox \\
(\theabc) & & \answerbox & \answerbox
\end{tabularx}
\end{enumerate}
\end{document}