( Humans ( ( have ( ( 23 pair ) ( of chromosomes ) ) ) . ) )
(ROOT (S (NP (NNS Humans)) (VP (VBP have) (NP (NP (CD 23) (NN pair)) (PP (IN of) (NP (NNS chromosomes))))) (. .)))
Humans have 23 pair of chromosomes.
(ROOT (S (NP (NNS Humans)) (VP (VBP have) (NP (NP (CD 23) (JJ pairs) (NNS pairs)) (PP (IN of) (NP (NNS chromosomes))))) (. .)))