( ( ( An increase ) ( in ( ( the pressure ) ( of ( the gas ) ) ) ) ) ( ( might ( be ( caused ( ( ( ( by ( ( an increase ) ( in temperature ) ) ) ( -LRB- ( ( through ( heating ( ( the container ) ( of ( the gas ) ) ) ) ) -RRB- ) ) ) or ) ( by ( ( ( a decrease ) ( in volume ) ) ( -LRB- ( ( through ( moving ( ( a piston ) ( connected ( to ( the container ) ) ) ) ) ) -RRB- ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT An) (NN increase)) (PP (IN in) (NP (NP (DT the) (NN pressure)) (PP (IN of) (NP (DT the) (NN gas)))))) (VP (MD might) (VP (VB be) (VP (VBN caused) (PP (PP (IN by) (NP (NP (DT an) (NN increase)) (PP (IN in) (NP (NN temperature))))) (PRN (-LRB- -LRB-) (PP (IN through) (S (VP (VBG heating) (NP (NP (DT the) (NN container)) (PP (IN of) (NP (DT the) (NN gas))))))) (-RRB- -RRB-)) (CC or) (PP (IN by) (NP (NP (DT a) (NN decrease)) (PP (IN in) (NP (NN volume))) (PRN (-LRB- -LRB-) (PP (IN through) (S (VP (VBG moving) (NP (NP (DT a) (NN piston)) (VP (VBN connected) (PP (TO to) (NP (DT the) (NN container)))))))) (-RRB- -RRB-)))))))) (. .)))
An increase in the pressure of the gas might be caused by an increase in temperature (through heating the container of the gas) or by a decrease in volume (through moving a piston connected to the container).
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NN gas) (NNS particles)) (VP (VB heat) (PRT (RP up))))) (, ,) (NP (NN pressure)) (VP (VBP increase)) (. .)))