\documentclass[a4paper]{article}

\usepackage[utf8x]{inputenc}    
\usepackage[T1]{fontenc}
\usepackage[box,completemulti]{automultiplechoice}    

\usepackage{tikz}

% macro to automatically create open choices
\makeatletter
\pgfkeys{
  lines/.store in=\@oc@lines,
  lines/.default=6,
  max/.store in=\@oc@max,
  max/.default=4,
  step/.store in=\@oc@step,
  step/.default=0.5
}
\newcommand{\AMCOpenChoices}[1][]{
  \pgfkeys{ %
    /pgf/number format/fixed,
    /pgf/number format/precision=1,
    lines, max, step, #1}
  \AMCOpen{lines=\@oc@lines,dots=false}{ %
    \pgfmathparse{\@oc@max-\@oc@step}%
    \foreach \i in {0, \@oc@step, ...,\pgfmathresult}{ %
      \pgfmathprintnumberto{\i}{\tmp}%
      \wrongchoice{\tmp}\scoring{\tmp}%
    }%
    \pgfmathprintnumberto{\@oc@max}{\tmp}%
    \correctchoice{\tmp}\scoring{\tmp}%
  }%
}
\makeatother


\begin{document}

\onecopy{1}{    

%%% beginning of the test sheet header:    

\noindent{\bf QCM  \hfill TEST}

\vspace*{.5cm}
\begin{minipage}{.4\linewidth}
\centering\large\bf Test\\ Examination on Jan., 1st, 2008\end{minipage}
\namefield{\fbox{    
                \begin{minipage}{.5\linewidth}
                  Firstname and lastname:

                  \vspace*{.5cm}\dotfill
                  \vspace*{1mm}
                \end{minipage}
         }}

\begin{center}\em
Duration : 10 minutes.

  No documents allowed. The use of electronic calculators is forbidden.


  Questions using the sign \multiSymbole{} may have
  zero, one or several correct answers.  Other questions have a single correct answer.

  Negative points may be attributed to \emph{very
    bad} answers.
\end{center}
\vspace{1ex}

%%% end of the header

\begin{question}{prez}    
  Among the following persons, which one has ever been a President of the French Republic?
  \begin{choices}
    \correctchoice{René Coty}
    \wrongchoice{Alain Prost}
    \wrongchoice{Marcel Proust}
    \wrongchoice{Claude Monet}
  \end{choices}
\end{question}

\begin{questionmult}{pref}    
  Among the following cities, which ones are French prefectures?
  \AMCOpenChoices[max=3]
\end{questionmult}

\begin{questionmult}{pref-manual}    
  Among the following cities, which ones are French prefectures?
  \AMCOpen{}{\wrongchoice{0}\scoring{0}\wrongchoice{1}\scoring{1}\wrongchoice{2}\scoring{2}\correctchoice{3}\scoring{3}}
\end{questionmult}

% \AMCaddpagesto{3} 8

}   

\end{document}
