to make us share their enthusiasm 
(ROOT (S (VP (TO to) (VP (VB make) (S (NP (PRP us)) (VP (VB share) (NP (PRP$ their) (NN enthusiasm))))))))
(ROOT (S (VP (TO ) (VP (VB ) (S (NP (PRP )) (VP (VB ) (NP (PRP$ ) (NN ))))))))