public function process_mc($xml, &$questions) {

        if ($this->getpath($xml, array('POOL', '#', 'QUESTION_MULTIPLECHOICE'), false, false)) {
            $mcquestions = $this->getpath($xml,
                    array('POOL', '#', 'QUESTION_MULTIPLECHOICE'), false, false);
        } else {
            return;
        }

        foreach ($mcquestions as $thisquestion) {

            $question = $this->process_common($thisquestion);

            $correctfeedback = $this->getpath($thisquestion,
                    array('#', 'GRADABLE', 0, '#', 'FEEDBACK_WHEN_CORRECT', 0, '#'),
                    '', true);
            $incorrectfeedback = $this->getpath($thisquestion,
                    array('#', 'GRADABLE', 0, '#', 'FEEDBACK_WHEN_INCORRECT', 0, '#'),
                    '', true);
            $question->correctfeedback = $this->cleaned_text_field($correctfeedback);
            $question->partiallycorrectfeedback = $this->text_field('');
            $question->incorrectfeedback = $this->cleaned_text_field($incorrectfeedback);

            $question->qtype = 'multichoice';
            $question->single = 1; // Only one answer is allowed.

            $choices = $this->getpath($thisquestion, array('#', 'ANSWER'), false, false);
            $correctanswerid = $this->getpath($thisquestion,
                        array('#', 'GRADABLE', 0, '#', 'CORRECTANSWER', 0, '@', 'answer_id'),
                        '', true);
            foreach ($choices as $choice) {
                $choicetext = $this->getpath($choice, array('#', 'TEXT', 0, '#'), '', true);
                // Put this choice in the question object.
                $question->answer[] = $this->cleaned_text_field($choicetext);

                $choiceid = $this->getpath($choice, array('@', 'id'), '', true);
                // If choice is the right answer, give 100% mark, otherwise give 0%.
                if (strcmp ($choiceid, $correctanswerid) == 0) {
                    $question->fraction[] = 1;
                } else {
                    $question->fraction[] = 0;
                }
                // There is never feedback specific to each choice.
                $question->feedback[] = $this->text_field('');
            }
            $questions[] = $question;
        }
    }