( ( Their tongues ) ( ( are ( used ( to ( feel things ) ) ) ) . ) )
(ROOT (S (NP (PRP$ Their) (NNS tongues)) (VP (VBP are) (VP (VBN used) (S (VP (TO to) (VP (VB feel) (NP (NNS things))))))) (. .)))
Their tongues are used to feel things.
(ROOT (S (NP (NNS Snakes)) (VP (VBP use) (NP (PRP$ their) (NN tongue)) (PP (TO to) (NP (NN smell) (NNS things)))) (. .)))
Snakes use their tongue to smell things.