They did this to us.
( They ( ( ( did this ) ( to us ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD did) (NP (DT this)) (PP (TO to) (NP (PRP us)))) (. .)))
They were all sick by what they had done to them.
( They ( ( ( were all ) ( sick ( by ( what ( they ( had ( done ( to them ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD were) (RB all) (ADJP (JJ sick) (PP (IN by) (SBAR (WHNP (WP what)) (S (NP (PRP they)) (VP (VBD had) (VP (VBN done) (PP (TO to) (NP (PRP them)))))))))) (. .)))