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)))) (. .)))
This was done by them.
( This ( ( was ( done ( by them ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBD was) (VP (VBN done) (PP (IN by) (NP (PRP them))))) (. .)))