( ( Rays ( in ( that plane ) ) ) ( ( ( form ( a ( second line-image ) ) ) ( at ( ( a ( different distance ) ) ( from ( the mirror ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Rays)) (PP (IN in) (NP (DT that) (NN plane)))) (VP (VBP form) (NP (DT a) (JJ second) (NN line-image)) (PP (IN at) (NP (NP (DT a) (JJ different) (NN distance)) (PP (IN from) (NP (DT the) (NN mirror)))))) (. .)))
Rays in that plane form a second line-image at a different distance from the mirror.
(ROOT (S (NP (NNP Plane) (NNS mirrors)) (VP (VBP work) (SBAR (IN because) (S (NP (DT the) (JJ light) (NNS rays)) (VP (VBP create) (NP (NP (DT a) (JJ virtual) (NN image)) (PP (IN behind) (NP (DT the) (NN mirror)))))))) (. .)))