( ( When ( ( fat ( from meat ) ) ( drips ( onto ( hot ( ( coals or ) stones ) ) ) ) ) ) ( , ( carcinogens ( ( called ( ( polycyclic ( aromatic hydrocarbons ) ) ( ( ( are formed ) and ) ( ( deposited ( onto food ) ) ( by ( ( ( smoke or ) flame-ups ) ( that ( ( ( char or ) blacken ) it ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NP (NN fat)) (PP (IN from) (NP (NN meat)))) (VP (VBZ drips) (PP (IN onto) (NP (JJ hot) (NNS coals) (CC or) (NNS stones)))))) (, ,) (NP (NNS carcinogens)) (VP (VBD called) (SBAR (S (NP (JJ polycyclic) (JJ aromatic) (NNS hydrocarbons)) (VP (VP (VBP are) (VP (VBN formed))) (CC and) (VP (VBD deposited) (PP (IN onto) (NP (NN food))) (PP (IN by) (NP (NP (NN smoke) (CC or) (NNS flame-ups)) (SBAR (WHNP (WDT that)) (S (VP (VBP char) (CC or) (VBP blacken) (NP (PRP it)))))))))))) (. .)))
When fat from meat drips onto hot coals or stones, carcinogens called polycyclic aromatic hydrocarbons are formed and deposited onto food by smoke or flame-ups that char or blacken it.
(ROOT (S (NP (PRP We)) (VP (VBP call) (NP (NP (DT the) (JJ solid) (NN form)) (PP (IN of) (NP (JJ hydrocarbons) (NN coal))))) (. .)))