likely to drown a viewer in boredom than to send any shivers down his spine 
(ROOT (ADJP (ADJP (JJ likely) (SBAR (S (VP (TO to) (VP (VB drown) (NP (DT a) (NN viewer)) (PP (IN in) (NP (NN boredom)))))))) (SBAR (IN than) (S (VP (TO to) (VP (VB send) (NP (DT any) (NNS shivers)) (PP (IN down) (NP (PRP$ his) (NN spine)))))))))
(ROOT (ADJP (ADJP (JJ ) (SBAR (S (VP (TO ) (VP (VB ) (NP (DT ) (NN )) (PP (IN ) (NP (NN )))))))) (SBAR (IN ) (S (VP (TO ) (VP (VB ) (NP (DT ) (NNS )) (PP (IN ) (NP (PRP$ ) (NN )))))))))