( ( An element ) ( ( is ( ( a ( pure substance ) ) ( that ( ( can not ) ( be ( ( ( broken down ) ( into ( anything simpler ) ) ) ( by ( ( ( chemical or ) physical ) means ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT An) (NN element)) (VP (VBZ is) (NP (NP (DT a) (JJ pure) (NN substance)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (RB not) (VP (VB be) (VP (VBN broken) (PRT (RP down)) (PP (IN into) (NP (NN anything) (NNS simpler))) (PP (IN by) (NP (ADJP (NN chemical) (CC or) (NN physical)) (NNS means)))))))))) (. .)))
An element is a pure substance that cannot be broken down into anything simpler by chemical or physical means.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (DT a) (JJ pure) (NN substance)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (RB not) (VP (VB be) (VP (VBN broken) (ADVP (RB down) (PP (IN into) (NP (NP (JJ different) (NNS types)) (PP (IN of) (NP (NNS substances)))))) (NP (DT a) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN element))))))))) (. .)))