(S (S (SBAR (WHADVP (WRB When)) (S (VP (VBN placed) (PP (IN in) (NP (BASENP (DT a) (NN mode)) (VP (VBG simulating) (BASENP (DT an) (JJ empty) (NN tank)))))))) (COMMA ,) (S (S (NP (BASENP (NN three)) (PP (IN of) (BASENP (DT the) (NNS sensors)))) (VP (ADVP (RB correctly)) (VP (VBD registered) (SBAR (IN that) (S (BASENP (DT the) (NN tank)) (VP (VBD was) (ADJP (JJ empty)))))))) (COMMA ,) (SBAR (IN while) (S (BASENP (DT the) (JJ faulty) (NN sensor)) (VP (VBD stayed) (PP (IN in) (BASENP (DT the) (QT (DQL ``) (JJ full) (DQR '')) (NN state)))))))) (PERIOD .))