like a comedian who starts off promisingly but then proceeds to flop , comedian runs out of steam after a half hour . 
(ROOT (S (PP (IN like) (NP (NP (DT a) (NN comedian)) (SBAR (WHNP (WP who)) (S (VP (VP (VBZ starts) (PRT (RP off)) (ADVP (RB promisingly))) (CC but) (ADVP (RB then)) (VP (VBZ proceeds) (S (VP (TO to) (VP (VB flop)))))))))) (, ,) (NP (NN comedian)) (VP (VBZ runs) (ADVP (IN out) (PP (IN of) (NP (NN steam)))) (PP (IN after) (NP (DT a) (JJ half) (NN hour)))) (. .)))
(ROOT (S (PP (IN ) (NP (NP (DT ) (NN )) (SBAR (WHNP (WP )) (S (VP (VP (VBZ ) (PRT (RP )) (ADVP (RB ))) (CC ) (ADVP (RB )) (VP (VBZ ) (S (VP (TO ) (VP (VB )))))))))) (, ) (NP (NN )) (VP (VBZ ) (ADVP (IN ) (PP (IN ) (NP (NN )))) (PP (IN ) (NP (DT ) (JJ ) (NN )))) (. )))