( ( A ( diverging ( -LRB- ( concave ( -RRB- lens ) ) ) ) ) ( ( ( can only ) ( form ( virtual images ) ) ) . ) )
(ROOT (S (NP (DT A) (VBG diverging) (-LRB- -LRB-) (NNP concave) (-RRB- -RRB-) (NN lens)) (VP (MD can) (ADVP (RB only)) (VP (VB form) (NP (JJ virtual) (NNS images)))) (. .)))
A diverging (concave) lens can only form virtual images.
(ROOT (S (NP (JJ Concave) (NNS lenses)) (VP (MD can) (VP (VB correct) (NP (NN myopia)))) (. .)))