have pulled off four similar kidnappings before 
(ROOT (S (VP (VBP have) (VP (VBN pulled) (PRT (RP off)) (NP (CD four) (JJ similar) (NNS kidnappings)) (ADVP (RB before))))))
(ROOT (S (VP (VBP ) (VP (VBN ) (PRT (RP )) (NP (CD ) (JJ ) (NNS )) (ADVP (RB ))))))