is such a perfect medium for children , 
(ROOT (S (VP (VBZ is) (NP (NP (PDT such) (DT a) (JJ perfect) (NN medium)) (PP (IN for) (NP (NNS children))))) (, ,)))
(ROOT (S (VP (VBZ ) (NP (NP (PDT ) (DT ) (JJ ) (NN )) (PP (IN ) (NP (NNS ))))) (, )))