hard to say who might enjoy this 
(ROOT (ADJP (JJ hard) (S (VP (TO to) (VP (VB say) (SBAR (WHNP (WP who)) (S (VP (MD might) (VP (VB enjoy) (NP (DT this)))))))))))
(ROOT (ADJP (JJ ) (S (VP (TO ) (VP (VB ) (SBAR (WHNP (WP )) (S (VP (MD ) (VP (VB ) (NP (DT )))))))))))