like leafing through an album of photos 
(ROOT (PP (IN like) (S (VP (VBG leafing) (PP (IN through) (NP (NP (DT an) (NN album)) (PP (IN of) (NP (NNS photos)))))))))
(ROOT (PP (IN ) (S (VP (VBG ) (PP (IN ) (NP (NP (DT ) (NN )) (PP (IN ) (NP (NNS )))))))))