def _add_pos_subtypes(nouns, verbs):
    """Combine alternating verbs and nouns into a new list.

    Args:
        nouns (list) - List of nouns, noun phrases, etc...
        verbs (list) - List of verbs, verb phrases, etc...

    Returns:
        words (list) - The newly combined list
    """
    words = []
    try:
        for noun in nouns:
            for verb in verbs:
                words.append('{} {}'.format(noun, verb))
                words.append('{} {}'.format(verb, noun))
    except KeyError:
        pass
    return words