( This ( ( ( ( is fortunate ) , ) ( since ( ( under ( ( the ( extreme conditions ) ) ( encountered ( in ( chemical ( and ( nuclear explosions ) ) ) ) ) ) ) ( , ( matter ( ( can usually ) ( be ( treated ( as ( ( a gas ) ( regardless ( of ( ( ( its density ) or ) ( original state ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBZ is) (ADJP (JJ fortunate)) (, ,) (SBAR (IN since) (S (PP (IN under) (NP (NP (DT the) (JJ extreme) (NNS conditions)) (VP (VBN encountered) (PP (IN in) (NP (JJ chemical) (CC and) (JJ nuclear) (NNS explosions)))))) (, ,) (NP (NN matter)) (VP (MD can) (ADVP (RB usually)) (VP (VB be) (VP (VBN treated) (PP (IN as) (NP (NP (DT a) (NN gas)) (ADVP (RB regardless) (PP (IN of) (NP (NP (PRP$ its) (NN density)) (CC or) (NP (JJ original) (NN state))))))))))))) (. .)))
This is fortunate, since under the extreme conditions encountered in chemical and nuclear explosions, matter can usually be treated as a gas regardless of its density or original state.
(ROOT (S (NP (NNS Gases)) (VP (VBP have) (NP (DT the) (JJS lowest) (NN density))) (. .)))