Postal Service could increase those same rates by at least 13.
( ( Postal Service ) ( ( could ( ( increase ( those ( same rates ) ) ) ( by ( ( at least ) 13 ) ) ) ) . ) )
(ROOT (S (NP (NNP Postal) (NNP Service)) (VP (MD could) (VP (VB increase) (NP (DT those) (JJ same) (NNS rates)) (PP (IN by) (NP (QP (IN at) (JJS least) (CD 13)))))) (. .)))
The rates can not be changed by the Postal Service.
( ( The rates ) ( ( ( can not ) ( be ( changed ( by ( the ( Postal Service ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNS rates)) (VP (MD can) (RB not) (VP (VB be) (VP (VBN changed) (PP (IN by) (NP (DT the) (NNP Postal) (NNP Service)))))) (. .)))