( ( The ( small intestine ) ) ( ( is ( where ( ( ( the majority ) ( of digestion ) ) ( takes place ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ small) (NN intestine)) (VP (VBZ is) (SBAR (WHADVP (WRB where)) (S (NP (NP (DT the) (NN majority)) (PP (IN of) (NP (NN digestion)))) (VP (VBZ takes) (NP (NN place)))))) (. .)))
The small intestine is where the majority of digestion takes place.
(ROOT (S (NP (NNP Chemical) (NNP digestion)) (ADVP (RB mainly)) (VP (VBZ occurs) (PP (IN in) (NP (DT the) (JJ small) (NN intestine)))) (. .)))