( ( The lathe ) ( ( can ( shape ( either ( ( ( a convex ) or ) ( a ( concave lens ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN lathe)) (VP (MD can) (VP (VB shape) (NP (CC either) (NP (DT a) (NN convex)) (CC or) (NP (DT a) (JJ concave) (NN lens))))) (. .)))
The lathe can shape either a convex or a concave lens.
(ROOT (S (NP (NP (DT The) (NN lens)) (PP (IN of) (NP (DT the) (NN eye)))) (VP (VBZ is) (S (NP (DT a) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN convex)) (VP (VB shape)))) (. .)))