( Humans ( ( have ( an ( open ( circulatory system ) ) ) ) . ) )
(ROOT (S (NP (NNS Humans)) (VP (VBP have) (NP (DT an) (JJ open) (NN circulatory) (NN system))) (. .)))
Humans have an open circulatory system.
(ROOT (S (NP (DT A) (NN jellyfish)) (VP (VBZ does) (RB not) (VP (VB have) (NP (DT a) (JJ circulatory) (NN system)))) (. .)))