public static Set<String> findWordsInterrogative(CompositeText document,
			int wordlength) {
		if (wordlength < 0) {
			LOGGER.error("Word length parameter must be positive");
			throw new IllegalArgumentException(
					"Word length parameter must be positive");
		}
		Set<String> words = new TreeSet<String>();
		Iterator<?> iterator = document.createIterator();
		while (iterator.hasNext()) {
			TextComponent sentence = (TextComponent) iterator.next();
			if (sentence.getName().equals(TextComponentName.SENTENCE)
					&& sentence.getType().equals(SentenceType.INTERROGATIVE)) {
				for (TextComponent token : sentence) {
					if (token.getType().equals(TokenType.WORD)) {
						String value = token.getValue();
						if (value.length() == wordlength) {
							words.add(value);
						}
					}
				}
			}
		}
		return words;
	}