puzzled by the mechanics of the delivery 
(ROOT (S (VP (VBN puzzled) (PP (IN by) (NP (NP (DT the) (NNS mechanics)) (PP (IN of) (NP (DT the) (NN delivery))))))))
(ROOT (S (VP (VBN ) (PP (IN ) (NP (NP (DT ) (NNS )) (PP (IN ) (NP (DT ) (NN ))))))))