Many who fled have returned.
( ( Many ( who fled ) ) ( ( have returned ) . ) )
(ROOT (S (NP (NP (JJ Many)) (SBAR (WHNP (WP who)) (S (VP (VBD fled))))) (VP (VBP have) (VP (VBN returned))) (. .)))
Lots of then came back.
( ( Lots ( of then ) ) ( ( came back ) . ) )
(ROOT (S (NP (NP (NNS Lots)) (PP (IN of) (NP (RB then)))) (VP (VBD came) (ADVP (RB back))) (. .)))