(S (COLON :) (QTL (DQL ``) (QTC (S (BASENP (DT The) (NN hydrocarbon) (NNS gases)) (VP (VBP are) (VP (VP (VBN burnt) (ADVP (RB safely))) (PP (IN into) (NP (NP (BASENP (NN water) (NN vapor)) (CC and) (BASENP (NN carbon) (NN dioxide))) (COMMA ,) (BASENP (CC both) (JJ harmless) (NNS gases))))))) (PERIOD .))))