They do not know it themselves.'  
( They ( ( ( ( do not ) ( know ( it themselves ) ) ) . ) ' ) )
(ROOT (S (NP (PRP They)) (VP (VBP do) (RB not) (VP (VB know) (S (NP (PRP it)) (NP (PRP themselves))))) (. .) ('' ')))
They know it all.
( They ( ( know ( it all ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP know) (S (NP (PRP it)) (NP (DT all)))) (. .)))