( ( ( The image ) ( formed ( by ( a ( plane mirror ) ) ) ) ) ( ( ( ( ( ( ( ( ( is ( neither ( ( enlarged nor ) reduced ) ) ) but ) ( ( is always ) virtual ) ) , ) erect ) , ) and ) ( appears ( to ( be ( behind ( the mirror ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN image)) (VP (VBN formed) (PP (IN by) (NP (DT a) (NN plane) (NN mirror))))) (VP (VP (VBZ is) (ADJP (DT neither) (JJ enlarged) (CC nor) (JJ reduced))) (CC but) (VP (VBZ is) (ADVP (RB always)) (ADJP (JJ virtual))) (, ,) (VP (VBZ erect)) (, ,) (CC and) (VP (VBZ appears) (S (VP (TO to) (VP (VB be) (PP (IN behind) (NP (DT the) (NN mirror)))))))) (. .)))
The image formed by a plane mirror is neither enlarged nor reduced but is always virtual, erect, and appears to be behind the mirror.
(ROOT (S (NP (DT A) (NN plane) (NN mirror)) (VP (VP (VBZ has) (NP (DT a) (ADJP (JJ flat) (JJ reflective)) (NN surface))) (CC and) (VP (VBZ forms) (NP (RB only) (JJ virtual) (NNS images)))) (. .)))