( ( Environmental pollutants ) ( ( ( do n't ) ( stop ( at borders ) ) ) . ) )
(ROOT (S (NP (JJ Environmental) (NNS pollutants)) (VP (VBP do) (RB n't) (VP (VB stop) (PP (IN at) (NP (NNS borders))))) (. .)))
Environmental pollutants don't stop at borders.
(ROOT (S (NP (NNS People)) (VP (VBD stopped) (S (VP (VBG adding) (NP (NN lead)) (PP (TO to) (NP (NP (NN gasoline)) (PP (RB because) (IN of) (NP (JJ environmental) (NN pollution)))))))) (. .)))