( ( ( Air and ) ( water pollution ) ) ( ( are ( ( the ( nation 's ) ) ( primary ( environmental concerns ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP Air)) (CC and) (NP (NN water) (NN pollution))) (VP (VBP are) (NP (NP (DT the) (NN nation) (POS 's)) (JJ primary) (JJ environmental) (NNS concerns))) (. .)))
Air and water pollution are the nation's primary environmental concerns.
(ROOT (S (NP (JJ Primary) (NNS pollutants)) (VP (VBP enter) (NP (DT the) (NN air)) (ADVP (RB directly))) (. .)))