( ( At ( ( the press ) ( of ( a button ) ) ) ) ( , ( ( gas pressure ) ( ( is ( ( ( ( increased or ) decreased ) , ) ( depending ( on need ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (NP (DT the) (NN press)) (PP (IN of) (NP (DT a) (NN button))))) (, ,) (NP (NN gas) (NN pressure)) (VP (VBZ is) (VP (VBN increased) (CC or) (VBN decreased) (, ,) (PP (VBG depending) (PP (IN on) (NP (NN need)))))) (. .)))
At the press of a button, gas pressure is increased or decreased, depending on need.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NN gas) (NNS particles)) (VP (VB heat) (PRT (RP up))))) (, ,) (NP (NN pressure)) (VP (VBP increase)) (. .)))