After four years, Clinton has learned how to avoid looking unpresidential.
( ( After ( four years ) ) ( , ( Clinton ( ( has ( learned ( how ( to ( avoid ( looking unpresidential ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN After) (NP (CD four) (NNS years))) (, ,) (NP (NNP Clinton)) (VP (VBZ has) (VP (VBN learned) (SBAR (WHADVP (WRB how)) (S (VP (TO to) (VP (VB avoid) (S (VP (VBG looking) (NP (NN unpresidential)))))))))) (. .)))
Four years later, Clinton understands how to look presidential.
( ( ( Four years ) later ) ( , ( Clinton ( ( understands ( how ( to ( look presidential ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (NP (CD Four) (NNS years)) (RB later)) (, ,) (NP (NNP Clinton)) (VP (VBZ understands) (SBAR (WHADVP (WRB how)) (S (VP (TO to) (VP (VB look) (ADJP (JJ presidential))))))) (. .)))