( ( Fuel NOx ) ( ( is ( ( formed ( by ( ( the reaction ) ( of nitrogen ) ) ) ) ( in ( ( the fuel ) ( with ( oxygen ( in ( the ( combustion air ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Fuel) (NNP NOx)) (VP (VBZ is) (VP (VBN formed) (PP (IN by) (NP (NP (DT the) (NN reaction)) (PP (IN of) (NP (NN nitrogen))))) (PP (IN in) (NP (NP (DT the) (NN fuel)) (PP (IN with) (NP (NP (NN oxygen)) (PP (IN in) (NP (DT the) (NN combustion) (NN air))))))))) (. .)))
Fuel NOx is formed by the reaction of nitrogen in the fuel with oxygen in the combustion air.
(ROOT (S (NP (NNP Combustion) (NN reaction)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NN substance)) (VP (VBZ reacts) (ADVP (RB quickly)) (PP (IN with) (NP (NN oxygen))))))) (. .)))