(S (S (S (BASENP (DT The) (NN find)) (VP (VBZ raises) (NP (BASENP (DT the) (NN possibility)) (PP (IN of) (NP (BASENP (NN life)) (PP (IN on) (BASENP (JJ other) (NNS planets)))))))) (COMMA ,) (SBAR (IN as) (S (BASENP (JJ liquid) (NN water)) (VP (VBZ is) (VP (VBN believed) (S (VP (TO to) (VP (VB be) (NP (BASENP (DT a) (NN requirement)) (PP (IN for) (BASENP (NN life)))))))))))) (PERIOD .))