private void recreateChoices(StringMatchingQuestion question) {
   question.clearSourceElement();
   question.clearTargetElement();
   System.out.println("Choices on the left side:");
   int numLeft = io.requestChoiceNumber();
   List<String> choicesLeft = io.requestMultipleStrings(numLeft, false);
   System.out.println("Choices on the right side:");
   int numRight = io.requestChoiceNumber();
   List<String> choicesRight = io.requestMultipleStrings(numRight, false);
   for (String s : choicesLeft) {
     question.addSourceElement(s);
   }
   for (String s : choicesRight) {
     question.addTargetElement(s);
   }
   enforceModify = true;
 }