( ( For example ) ( , ( ( ( the burning ) ( of wood ) ) ( ( ( is spontaneous ) ( once ( ( the fire ) ( is started ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (NN example))) (, ,) (NP (NP (DT the) (NN burning)) (PP (IN of) (NP (NN wood)))) (VP (VBZ is) (ADJP (JJ spontaneous)) (SBAR (IN once) (S (NP (DT the) (NN fire)) (VP (VBZ is) (VP (VBN started)))))) (. .)))
For example, the burning of wood is spontaneous once the fire is started.
(ROOT (S (NP (NNP Wood) (NNP burning)) (VP (VBZ is) (NP (NP (DT an) (NN example)) (PP (IN of) (NP (NP (DT a) (JJ different) (NN substance)) (VP (VBG being) (VP (VBN formed))))))) (. .)))