( ( These ( two ( mass balances ) ) ) ( follow . ) )
(ROOT (S (NP (DT These) (CD two) (JJ mass) (NNS balances)) (VP (VBP follow)) (. .)))
These two mass balances follow.
(ROOT (S (NP (DT A) (NN student)) (VP (MD should) (VP (VB use) (NP (DT a) (NN balance) (S (VP (TO to) (VP (VB compare) (NP (NP (DT the) (NNS masses)) (PP (IN of) (NP (CD two) (JJ small) (NNS rocks)))))))))) (. .)))