( ( For example ) ( , ( water ( ( is ( ( ( H ( 2 O ) ) , ) ( which ( means ( there ( are ( ( ( ( 2 atoms ) ( of hydrogen ) ) and ) ( ( one atom ) ( of ( oxygen ( in ( the molecule ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (NN example))) (, ,) (NP (NN water)) (VP (VBZ is) (NP (NP (NNP H) (CD 2) (NN O)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ means) (SBAR (S (NP (EX there)) (VP (VBP are) (NP (NP (NP (CD 2) (NNS atoms)) (PP (IN of) (NP (NN hydrogen)))) (CC and) (NP (NP (CD one) (NN atom)) (PP (IN of) (NP (NP (NN oxygen)) (PP (IN in) (NP (DT the) (NN molecule))))))))))))))) (. .)))
For example, water is H 2 O , which means there are 2 atoms of hydrogen and one atom of oxygen in the molecule.
(ROOT (S (NP (NP (CD 2) (NN hydrogen)) (, ,) (NP (CD 1) (NN oxygen) (NNS atoms))) (VP (VBP combine) (S (VP (TO to) (VP (VB make) (PRT (RP up)) (NP (NP (DT a) (NN molecule)) (PP (IN of) (NP (NN water)))))))) (. .)))
2 hydrogen, 1 oxygen atoms combine to make up a molecule of water.