( ( As ( soon ( as ( ( the bread ) ( enters ( ( a ( person 's ) ) mouth ) ) ) ) ) ) ( , ( digestion ( ( begins ( to occur ) ) . ) ) ) )
(ROOT (S (ADVP (RB As) (RB soon) (SBAR (IN as) (S (NP (DT the) (NN bread)) (VP (VBZ enters) (NP (NP (DT a) (NN person) (POS 's)) (NN mouth)))))) (, ,) (NP (NN digestion)) (VP (VBZ begins) (S (VP (TO to) (VP (VB occur))))) (. .)))
As       soon as the bread enters a person's mouth, digestion begins to       occur.
(ROOT (S (NP (NNP Digestion)) (VP (VBZ begins) (PP (IN in) (NP (DT the) (NN mouth)))) (. .)))