( ( ( Subject matter ) ( wherein ( ( the ( thermal energy ) ) ( is ( in ( ( the form ) ( of ( ( ( radiant heat ) or ) ( the ( thermal energy ) ) ) ) ) ) ) ) ) ) ( ( is ( produced ( by ( radio ( frequency heating ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Subject) (NN matter)) (SBAR (WHADVP (WRB wherein)) (S (NP (DT the) (JJ thermal) (NN energy)) (VP (VBZ is) (PP (IN in) (NP (NP (DT the) (NN form)) (PP (IN of) (NP (NP (JJ radiant) (NN heat)) (CC or) (NP (DT the) (JJ thermal) (NN energy)))))))))) (VP (VBZ is) (VP (VBN produced) (PP (IN by) (NP (NN radio) (NN frequency) (NN heating))))) (. .)))
Subject matter wherein the thermal energy is in the form of radiant heat or the thermal energy is produced by radio frequency heating.
(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.