( ( The gas ) ( ( is ( burned ( to ( ( produce energy ) ( to ( ( ( ( ( ( heat homes ) , ) business ) , ) and ) ( industrial plants ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN gas)) (VP (VBZ is) (VP (VBN burned) (S (VP (TO to) (VP (VB produce) (NP (NN energy)) (PP (TO to) (NP (NP (NN heat) (NNS homes)) (, ,) (NP (NN business)) (, ,) (CC and) (NP (JJ industrial) (NNS plants))))))))) (. .)))
The gas is burned to produce energy to heat homes, business, and industrial plants.
(ROOT (S (NP (NNP Heat)) (VP (VBZ is) (VP (VBN produced) (SBAR (WHADVP (WRB when)) (S (NP (NN paper)) (VP (VBZ is) (VP (VBN burned))))))) (. .)))
Heat is produced when paper is burned.