( This ( ( ( ( is ( ( much greater ) ( than ( ( the density ) ( of ( nuclear matter ) ) ) ) ) ) , ) ( for example ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBZ is) (ADJP (ADJP (RB much) (JJR greater)) (PP (IN than) (NP (NP (DT the) (NN density)) (PP (IN of) (NP (JJ nuclear) (NN matter)))))) (, ,) (PP (IN for) (NP (NN example)))) (. .)))
This is much greater than the density of nuclear matter, for example.
(ROOT (S (NP (NNP Density)) (VP (VBZ describes) (SBAR (WHADJP (WRB how) (JJ much)) (S (NP (NN matter)) (VP (VBZ is) (PP (IN in) (NP (NP (DT a) (JJ certain) (NN amount)) (PP (IN of) (NP (NN space))))))))) (. .)))