['it', 'keep', 'they', 'EmptyParameter', 'EmptyParameter']
['<PRP>', 'keep-15.2', '<PRP>', 'EmptyParameter', 'EmptyParameter']
It will keep them from being attacked by ships that are obviously more advanced.
<PRP> will keep <PRP> from being attacked by Synset('craft.n.02') that are obviously more advanced.