['they', 'consider', 'possibility', 'EmptyParameter', 'EmptyParameter']
['<PRP>', 'consider-29.9-1-1-1', "Synset('idea.n.01')", 'EmptyParameter', 'EmptyParameter']
Logically, they must consider the possibility.
Logically, <PRP> must consider the Synset('idea.n.01').