(S (S (BASENP (DT The) (NN sensor)) (VP (VBZ is) (NP (BASENP (NN one)) (PP (IN of) (NP (BASENP (NN four)) (VP (VBN used) (S (VP (TO to) (VP (VP (VB trigger) (BASENP (DT the) (NN engine) (NN cutout))) (PP (IN after) (BASENP (NN launch)))))))))))) (PERIOD .))