also is difficult to fathom . 
(ROOT (S (ADVP (RB also)) (VP (VBZ is) (ADJP (JJ difficult) (SBAR (S (VP (TO to) (VP (VB fathom))))))) (. .)))
(ROOT (S (ADVP (RB )) (VP (VBZ ) (ADJP (JJ ) (SBAR (S (VP (TO ) (VP (VB ))))))) (. )))