( ( ( The volume ) ( of ( a gas ) ) ) ( ( will ( increase ( if ( ( the pressure ) ( is lowered ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN volume)) (PP (IN of) (NP (DT a) (NN gas)))) (VP (MD will) (VP (VB increase) (SBAR (IN if) (S (NP (DT the) (NN pressure)) (VP (VBZ is) (VP (VBN lowered))))))) (. .)))
The volume of a gas will increase if the pressure is lowered.
(ROOT (S (PP (IN From) (NP (NP (NNS observations)) (ADJP (RB as) (JJ simple) (PP (IN as) (S (VP (VBG blowing) (PRT (RP up)) (NP (DT a) (NN balloon)))))))) (, ,) (NP (PRP it)) (VP (VBZ is) (ADJP (JJ clear)) (SBAR (IN that) (S (S (VP (VBG increasing) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN gas)))))) (VP (VBZ increases) (NP (DT the) (NN volume)))))) (. .)))