has been gathering dust on mgm 's shelf 
(ROOT (S (VP (VBZ has) (VP (VBN been) (VP (VBG gathering) (NP (NN dust)) (PP (IN on) (NP (NP (NNP mgm) (POS 's)) (NN shelf))))))))
(ROOT (S (VP (VBZ ) (VP (VBN ) (VP (VBG ) (NP (NN )) (PP (IN ) (NP (NP (NNP ) (POS )) (NN ))))))))