Poirot answered them categorically, almost mechanically. 
( ( ( ( Poirot ( ( answered them ) categorically ) ) , ) ( almost mechanically ) ) . )
(ROOT (S (S (NP (NNP Poirot)) (VP (VBD answered) (NP (PRP them)) (ADVP (RB categorically)))) (, ,) (FRAG (ADJP (RB almost) (RB mechanically))) (. .)))
Poirot responded to them categorically, like a machine.
( Poirot ( ( ( ( ( responded ( to them ) ) categorically ) , ) ( like ( a machine ) ) ) . ) )
(ROOT (S (NP (NNP Poirot)) (VP (VBD responded) (PP (TO to) (NP (PRP them))) (ADVP (RB categorically)) (, ,) (PP (IN like) (NP (DT a) (NN machine)))) (. .)))