( Density ( ( is ( ( the amount ) ( of ( mass ( in ( a ( specified space ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Density)) (VP (VBZ is) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN mass)) (PP (IN in) (NP (DT a) (VBN specified) (NN space))))))) (. .)))
Density is the amount of mass in a specified space.
(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))))))))) (. .)))