( ( A ( railroad track ) ) ( ( extends ( ( the length ) ( of ( ( the ( eastern edge ) ) ( of ( the ( two units ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN railroad) (NN track)) (VP (VBZ extends) (NP (NP (DT the) (NN length)) (PP (IN of) (NP (NP (DT the) (JJ eastern) (NN edge)) (PP (IN of) (NP (DT the) (CD two) (NNS units))))))) (. .)))
A railroad track extends the length of the eastern edge of the two units.
(ROOT (S (NP (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN increase)) (PP (IN in) (NP (NN length)))) (VP (VBZ happens) (PP (TO to) (NP (NN metal) (NN railroad) (NNS tracks))) (PP (IN during) (NP (NP (DT the) (NN heat)) (PP (IN of) (NP (DT a) (NN summer) (NN day)))))) (. .)))