['they', 'detect', 'sign', 'EmptyParameter', 'EmptyParameter']
['<PRP>', 'see-30.1', "Synset('location.n.01')", 'EmptyParameter', 'EmptyParameter']
They then detect faint life signs underneath the city.
<PRP> then detect faint Synset('record.n.01') Synset('location.n.01') underneath the Synset('gathering.n.01').