['they', 'know', 'EmptyParameter', 'EmptyParameter', 'EmptyParameter'] ['they', 'find', 'EmptyParameter', 'EmptyParameter', 'EmptyParameter']
['<PRP>', 'comprehend-87.2', 'EmptyParameter', 'EmptyParameter', 'EmptyParameter'] ['<PRP>', 'declare-29.4', 'EmptyParameter', 'EmptyParameter', 'EmptyParameter']
They can not know for certain what they will find.
<PRP> can not know for Synset('certain.a.04') what <PRP> will find.