( ( Burning ( of ( fossil fuels ) ) ) ( ( is ( ( the ( major factor ) ) ( generating ( oxides ( of ( ( ( ( sulfur and ) nitrogen ) , ) ( which ( are ( ( converted ( into ( ( ( nitric and ) sulfuric ) acids ) ) ) ( when ( mixed ( with ( atmospheric water ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NN Burning)) (PP (IN of) (NP (JJ fossil) (NNS fuels)))) (VP (VBZ is) (NP (NP (DT the) (JJ major) (NN factor)) (VP (VBG generating) (NP (NP (NNS oxides)) (PP (IN of) (NP (NP (NN sulfur) (CC and) (NN nitrogen)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBP are) (VP (VBN converted) (PP (IN into) (NP (ADJP (JJ nitric) (CC and) (JJ sulfuric)) (NNS acids))) (SBAR (WHADVP (WRB when)) (S (VP (VBN mixed) (PP (IN with) (NP (JJ atmospheric) (NN water)))))))))))))))) (. .)))
Burning of fossil fuels is the major factor generating oxides of sulfur and nitrogen, which are converted into nitric and sulfuric acids when mixed with atmospheric water.
(ROOT (S (NP (DT The) (NN element) (NN sulfur)) (VP (VBZ is) (VP (VBN released) (PP (IN into) (NP (DT the) (NN atmosphere))) (PP (IN by) (NP (NP (DT the) (NN burning)) (PP (IN of) (NP (JJ fossil) (NNS fuels))))))) (. .)))