TheSalkvaccineisamajorfactorinthefighttoeradicatepolio.
Despite the proliferation of other faster modes of transportation, the railroads remain the largest carriers of intercity freight in the United States.
Alligatorsstillexistinsomeofthedank潮湿swampsandbayous小海湾ofAlabama'scoastalregions.
Insect pests are among the leading causes of crop failure.
ThefuturesurvivalofthebaldeagleisstillanimportantAmericanecologicalconcern.