(S (S (BASENP (PRP It)) (VP (VP (VBZ is) (VP (VBN estimated))) (SBAR (IN that) (S (BASENP (EX there)) (VP (VBZ is) (NP (NP (BASENP (QP (NN five) (TO to) (NN six)) (NNS days)) (PP (IN of) (BASENP (JJ breathable) (NN air)))) (VP (VBN left) (PP (IN in) (BASENP (DT the) (NN mine)))))))))) (PERIOD .))