( ( ( Inert gases ) ( -LRB- ( ( most often ) ( ( ( ( carbon dioxide ) and ) water ) -RRB- ) ) ) ) ( ( ( ( ( produced ( by ( ( thermal degradation ) ( of ( some ( materials act ) ) ) ) ) ) ( as ( diluents ( of ( the ( combustible gases ) ) ) ) ) ) , ) ( ( ( ( lowering ( ( ( their ( partial pressures ) ) and ) ( ( the ( partial pressure ) ) ( of oxygen ) ) ) ) , ) and ) ( slowing ( the ( reaction rate ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Inert) (NNS gases)) (PRN (-LRB- -LRB-) (ADVP (RBS most) (RB often)) (NP (NP (NN carbon) (NN dioxide)) (CC and) (NP (NN water))) (-RRB- -RRB-))) (VP (VBD produced) (PP (IN by) (NP (NP (JJ thermal) (NN degradation)) (PP (IN of) (NP (DT some) (NNS materials) (NN act))))) (PP (IN as) (NP (NP (NNS diluents)) (PP (IN of) (NP (DT the) (JJ combustible) (NNS gases))))) (, ,) (S (VP (VP (VBG lowering) (NP (NP (PRP$ their) (JJ partial) (NNS pressures)) (CC and) (NP (NP (DT the) (JJ partial) (NN pressure)) (PP (IN of) (NP (NN oxygen)))))) (, ,) (CC and) (VP (VBG slowing) (NP (DT the) (NN reaction) (NN rate)))))) (. .)))
Inert gases (most often carbon dioxide and water) produced by thermal degradation of some materials act as diluents of the combustible gases, lowering their partial pressures and the partial pressure of oxygen, and slowing the reaction rate.
(ROOT (S (NP (NNP Combustion) (NNS reactions)) (VP (VBP involve) (S (NP (NP (DT the) (NN reaction)) (PP (IN of) (NP (NP (DT a) (NN hydrocarbon)) (PP (IN with) (NP (NN oxygen) (NN gas)))))) (VP (TO to) (VP (VB produce) (NP (NN water) (CC and) (NN carbon) (NN dioxide)))))) (. .)))