What idiots girls are! 
( ( What ( ( idiots girls ) are ) ) ! )
(ROOT (FRAG (SBAR (WHNP (WP What)) (S (NP (NNS idiots) (NNS girls)) (VP (VBP are)))) (. !)))
They thought the girls were stupid.
( They ( ( thought ( ( the girls ) ( were stupid ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD thought) (SBAR (S (NP (DT the) (NNS girls)) (VP (VBD were) (ADJP (JJ stupid)))))) (. .)))