( ( ( Sulfur and ) oxygen ) ( ( can ( form ( ( ( ( sulfur dioxide ) ( -LRB- ( ( SO 2 ) -RRB- ) ) ) and ) ( ( sulfur trioxide ) ( -LRB- ( ( SO 3 ) -RRB- ) ) ) ) ) ) . ) )
(ROOT (S (NP (NN Sulfur) (CC and) (NN oxygen)) (VP (MD can) (VP (VB form) (NP (NP (NP (NN sulfur) (NN dioxide)) (PRN (-LRB- -LRB-) (NP (NNP SO) (CD 2)) (-RRB- -RRB-))) (CC and) (NP (NP (NN sulfur) (NN trioxide)) (PRN (-LRB- -LRB-) (NP (NNP SO) (CD 3)) (-RRB- -RRB-)))))) (. .)))
Sulfur and oxygen can form sulfur dioxide (SO 2 ) and sulfur trioxide (SO 3 ).
(ROOT (S (NP (NNP Sulfur)) (VP (MD can) (VP (VB combine) (PP (IN with) (NP (NN oxygen))) (S (VP (TO to) (VP (VB produce) (NP (NN sulfur) (NN trioxide))))))) (. .)))