( ( When ( we ( burn wood ) ) ) ( , ( ( chemical energy ) ( ( is ( converted ( into heat ) ) ) ; ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (PRP we)) (VP (VBP burn) (NP (NN wood))))) (, ,) (NP (NN chemical) (NN energy)) (VP (VBZ is) (VP (VBN converted) (PP (IN into) (NP (NN heat))))) (: ;)))
When we burn wood, chemical energy is converted into heat;
(ROOT (S (S (NP (DT The) (NN energy)) (VP (VBZ transformations) (SBAR (IN that) (S (VP (VBP occur) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NN candle) (NNS burns)) (VP (VBZ is) (VP (VBN described) (PP (IN by))))))))))) (: :) (S (NP (NP (NN chemical) (NN energy)) (PP (IN from) (NP (DT the) (NN wax)))) (VP (VBZ is) (VP (VBN converted) (PP (IN into) (NP (NN light) (CC and) (NN heat) (NN energy)))))) (. .)))