( ( A punk ) ( ( is ( ( a ( long ( , ( thin piece ) ) ) ) ( of ( wood ( covered ( in ( ( ( ( a substance ) ( that ( ( ( burns ( very slowly ) ) , ) ( producing ( only heat ) ) ) ) ) , ) ( with ( no flame ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN punk)) (VP (VBZ is) (NP (NP (DT a) (JJ long) (, ,) (JJ thin) (NN piece)) (PP (IN of) (NP (NP (NN wood)) (VP (VBN covered) (PP (IN in) (NP (NP (DT a) (NN substance)) (SBAR (WHNP (WDT that)) (S (VP (VBZ burns) (ADVP (RB very) (RB slowly)) (, ,) (S (VP (VBG producing) (NP (JJ only) (NN heat))))))) (, ,) (PP (IN with) (NP (DT no) (NN flame)))))))))) (. .)))
A punk is a long, thin piece of wood covered in a substance that burns very slowly, producing only heat, with no flame.
(ROOT (S (NP (NP (DT The) (NN action)) (PP (IN of) (S (VP (VBG burning) (NP (NP (DT a) (NN piece)) (PP (IN of) (NP (NN wood)))))))) (VP (VBZ forms) (NP (DT a) (JJ different) (NN chemical) (NN substance))) (. .)))