['they', 'find', 'another', 'EmptyParameter', 'EmptyParameter']
['<PRP>', 'declare-29.4', 'another', 'EmptyParameter', 'EmptyParameter']
The planet's atmosphere is unstable and that they must find another.
the planet's Synset('unit_of_measurement.n.01') is Synset('unstable.a.01') and that <PRP> must find another.