His vigorous strides soon enabled him to gain upon them, and by the time he, in his turn, reached the corner the distance between them was sensibly lessened.
( ( His ( vigorous strides ) ) ( soon ( ( enabled ( him ( to ( gain ( ( ( ( upon them ) , ) and ) ( by ( ( the time ) ( he ( , ( ( in ( his turn ) ) ( , ( reached ( ( the corner ) ( ( ( the distance ) ( between them ) ) ( was ( sensibly lessened ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (PRP$ His) (JJ vigorous) (NNS strides)) (ADVP (RB soon)) (VP (VBD enabled) (S (NP (PRP him)) (VP (TO to) (VP (VB gain) (PP (PP (IN upon) (NP (PRP them))) (, ,) (CC and) (PP (IN by) (NP (NP (DT the) (NN time)) (SBAR (S (NP (PRP he)) (, ,) (PP (IN in) (NP (PRP$ his) (NN turn))) (, ,) (VP (VBD reached) (NP (NP (DT the) (NN corner)) (SBAR (S (NP (NP (DT the) (NN distance)) (PP (IN between) (NP (PRP them)))) (VP (VBD was) (ADJP (RB sensibly) (JJ lessened)))))))))))))))) (. .)))
He walked quickly after them, having gained considerably upon rounding the corner.
( He ( ( ( ( ( walked quickly ) ( after them ) ) , ) ( having ( ( gained considerably ) ( upon ( rounding ( the corner ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBD walked) (ADVP (RB quickly)) (PP (IN after) (NP (PRP them))) (, ,) (S (VP (VBG having) (VP (VBN gained) (ADVP (RB considerably)) (PP (IN upon) (S (VP (VBG rounding) (NP (DT the) (NN corner))))))))) (. .)))