( ( Much ( of ( ( the mass ) ( of ( the universe ) ) ) ) ) ( ( is ( ( ( contained ( in ( ( clouds ( of ( ( gas and ) dust ) ) ) ( that ( pervade ( the ( interstellar medium ) ) ) ) ) ) ) and ) ( ( come together ) ( in nebulae ) ) ) ) . ) )
(ROOT (S (NP (NP (RB Much)) (PP (IN of) (NP (NP (DT the) (NN mass)) (PP (IN of) (NP (DT the) (NN universe)))))) (VP (VBZ is) (VP (VP (VBN contained) (PP (IN in) (NP (NP (NNS clouds)) (PP (IN of) (NP (NN gas) (CC and) (NN dust))) (SBAR (WHNP (WDT that)) (S (VP (VBP pervade) (NP (DT the) (NN interstellar) (NN medium)))))))) (CC and) (VP (VBN come) (ADVP (RB together)) (PP (IN in) (NP (NN nebulae)))))) (. .)))
Much of the mass of the universe is contained in clouds of gas and dust that pervade the interstellar medium and come together in nebulae.
(ROOT (S (NP (JJ Interstellar) (NN medium)) (VP (VBZ consists) (PP (IN of) (NP (NP (RB thinly) (NN spread) (NN gas)) (CC and) (NP (NN dust))))) (. .)))