They even smiled at Susan and she smiled back.
( ( ( ( They ( even ( smiled ( at Susan ) ) ) ) and ) ( she ( smiled back ) ) ) . )
(ROOT (S (S (NP (PRP They)) (ADVP (RB even)) (VP (VBD smiled) (PP (IN at) (NP (NNP Susan))))) (CC and) (S (NP (PRP she)) (VP (VBD smiled) (ADVP (RB back)))) (. .)))
They frowned at Susan.
( They ( ( frowned ( at Susan ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD frowned) (PP (IN at) (NP (NNP Susan)))) (. .)))