, to say nothing of boring . 
(ROOT (S (, ,) (S (VP (TO to) (VP (VB say) (NP (NP (NN nothing)) (PP (IN of) (NP (JJ boring))))))) (. .)))
(ROOT (S (, ) (S (VP (TO ) (VP (VB ) (NP (NP (NN )) (PP (IN ) (NP (JJ ))))))) (. )))