that 's always fun to watch 
(ROOT (S (NP (DT that)) (VP (VBZ 's) (ADVP (RB always)) (ADJP (JJ fun)) (S (VP (TO to) (VP (VB watch)))))))
(ROOT (S (NP (DT )) (VP (VBZ ) (ADVP (RB )) (ADJP (JJ )) (S (VP (TO ) (VP (VB )))))))