Then he gave in.
( Then ( he ( ( gave in ) . ) ) )
(ROOT (S (RB Then) (NP (PRP he)) (VP (VBD gave) (PRT (RP in))) (. .)))
He gave in to the pain.
( He ( ( gave ( in ( to ( the pain ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBD gave) (PP (IN in) (PP (TO to) (NP (DT the) (NN pain))))) (. .)))