['sensor', 'have', 'nothing', 'EmptyParameter', 'EmptyParameter'] ['they', 'have', 'nothing', 'EmptyParameter', 'EmptyParameter']
["Synset('instrumentality.n.03')", 'own-100', "Synset('measure.n.02')", 'EmptyParameter', 'EmptyParameter'] ['<PRP>', 'own-100', "Synset('measure.n.02')", 'EmptyParameter', 'EmptyParameter']
Then navigational sensors, which had all the time been silent as they had nothing to detect, begin beeping.
then Synset('navigational.a.01') sensors, which had all the Synset('abstraction.n.06') been silent as <PRP> had Synset('measure.n.02') to detect, begin beeping.