are all things we 've seen before 
(ROOT (VP (VBP are) (NP (NP (DT all) (NNS things)) (SBAR (S (NP (PRP we)) (VP (VBP 've) (VP (VBN seen) (ADVP (RB before)))))))))
(ROOT (VP (VBP ) (NP (NP (DT ) (NNS )) (SBAR (S (NP (PRP )) (VP (VBP ) (VP (VBN ) (ADVP (RB )))))))))