['they', 'see', 'distance', 'EmptyParameter', 'EmptyParameter']
['<PRP>', 'see-30.1-1-1', "Synset('measure.n.02')", 'EmptyParameter', 'EmptyParameter']
They can only see a distance of several light years ahead.
<PRP> can only see a Synset('measure.n.02') of several Synset('light.a.03') Synset('fundamental_quantity.n.01') ahead.