marveling at these guys ' superhuman capacity to withstand pain 
(ROOT (S (VP (VBG marveling) (PP (IN at) (NP (NP (DT these) (NNS guys) (POS ')) (JJ superhuman) (NN capacity) (S (VP (TO to) (VP (VB withstand) (NP (NN pain))))))))))
(ROOT (S (VP (VBG ) (PP (IN ) (NP (NP (DT ) (NNS ) (POS )) (JJ ) (NN ) (S (VP (TO ) (VP (VB ) (NP (NN ))))))))))