( ( Chemicals ( ( needed ( in ( the ( small intestine ) ) ) ) ( to ( aid digestion ) ) ) ) ( ( ( can not ) ( get through ) ) . ) )
(ROOT (S (NP (NP (NNS Chemicals)) (VP (VBN needed) (PP (IN in) (NP (DT the) (JJ small) (NN intestine))) (PP (TO to) (NP (NN aid) (NN digestion))))) (VP (MD can) (RB not) (VP (VB get) (PRT (RP through)))) (. .)))
Chemicals needed in the small intestine to aid digestion cannot get through.
(ROOT (S (PP (IN In) (NP (DT the) (NN body))) (, ,) (NP (NN chemical) (NN digestion)) (ADVP (RB mainly)) (VP (VBZ takes) (NP (NP (NN place)) (PP (IN in) (NP (DT the) (JJ small) (NN intestine))))) (. .)))
In the body, chemical digestion mainly takes place in the small intestine.