In 1861 it seemed inevitable that the Southern states would break away from the Union.
A、strangeB
暂无解析
ThecompanyissuesanannualreporteveryMarch.
TheSalkvaccineisamajorfactorinthefighttoeradicatepolio.
Thecontrolsofmostmodernairplanescanbeoperatedeithermanuallyorautomatically.
Batsfly,ratherthanglide,andthusaretheonlymammalscapableoftrueflight.
Communicationisoneofthemostimportantbondsthatholdculturalsystemstogether.
