['she', 'put', 'finger', 'EmptyParameter', 'EmptyParameter']
['<PRP>', 'put-9.1-2', "Synset('artifact.n.01')", 'EmptyParameter', 'EmptyParameter']
She couldn't put her finger on what exactly.
<PRP> couldn't put <PRP> Synset('artifact.n.01') on what exactly.