been replaced by the bottom of the barrel 
(ROOT (VP (VBN been) (VP (VBN replaced) (PP (IN by) (NP (NP (DT the) (NN bottom)) (PP (IN of) (NP (DT the) (NN barrel))))))))
(ROOT (VP (VBN ) (VP (VBN ) (PP (IN ) (NP (NP (DT ) (NN )) (PP (IN ) (NP (DT ) (NN ))))))))