[lemma=have] [tag=□] □
[lemma=have] [tag=DT] □
Thus , it is important to have a robust and comprehensive causal model that explains how these consequences arise so as to help all parties involved to prevent these consequences . We did n't have the fangs , claws , or speed necessary to make good predators ; we did n't have the robust and complicated digestive systems necessary for successful browsing or grazing , so we could n't live on grasses and shrubs .