( ( ( ( All sexually ) reproducing ) organisms ) ( have ( ( an alternation ) ( of generations ) ) ) )
(ROOT (S (NP (ADJP (NP (DT All) (RB sexually)) (JJ reproducing)) (NNS organisms)) (VP (VBP have) (NP (NP (DT an) (NN alternation)) (PP (IN of) (NP (NNS generations)))))))
All sexually reproducing organisms have an alternation of generations
(ROOT (S (NP (DT All)) (VP (VBZ vertebrates) (VP (VB reproduce) (ADVP (RB sexually)))) (. .)))