( PAHs ( ( are ( ( a group ) ( of ( ( ( more ( than 100 ) ) ( different chemicals ) ) ( that ( are ( formed ( during ( ( ( the burning ) ( of ( coal ( , ( oil ( and ( gas ( , ( garbage ( or ( other ( organic substances ) ) ) ) ) ) ) ) ) ) ) ) ( such ( as ( ( tobacco or ) ( charbroiled meat ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS PAHs)) (VP (VBP are) (NP (NP (DT a) (NN group)) (PP (IN of) (NP (NP (QP (JJR more) (IN than) (CD 100)) (JJ different) (NNS chemicals)) (SBAR (WHNP (WDT that)) (S (VP (VBP are) (VP (VBN formed) (PP (IN during) (NP (NP (DT the) (NN burning)) (PP (IN of) (NP (NN coal) (, ,) (NN oil) (CC and) (NN gas) (, ,) (NN garbage) (CC or) (JJ other) (JJ organic) (NNS substances))) (PP (JJ such) (IN as) (NP (NP (NN tobacco)) (CC or) (NP (JJ charbroiled) (NN meat)))))))))))))) (. .)))
PAHs are a group of more than 100 different chemicals that are formed during the burning of coal, oil and gas, garbage or other organic substances such as tobacco or charbroiled meat.
(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))))))) (. .)))