( ( For ( this reason ) ) ( , ( ( a ( double ( concave lens ) ) ) ( ( ( can never ) ( produce ( a ( real image ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN For) (NP (DT this) (NN reason))) (, ,) (NP (DT a) (JJ double) (NN concave) (NN lens)) (VP (MD can) (ADVP (RB never)) (VP (VB produce) (NP (DT a) (JJ real) (NN image)))) (. .)))
For this reason, a double concave lens can never produce a real image.
(ROOT (S (NP (JJ Concave) (NNS lenses)) (VP (MD can) (VP (VB correct) (NP (NN myopia)))) (. .)))