def filter_insignificant(chunk, tag_suffixes=('DT', 'CC', 'PRP$', 'PRP')):
    """Filter out insignificant (word, tag) tuples from a chunk of text."""
    good = []
    for word, tag in chunk:
        ok = True
        for suffix in tag_suffixes:
            if tag.endswith(suffix):
                ok = False
                break
        if ok:
            good.append((word, tag))
    return good