The future survival of the bald eagle is still an important American ecological concern.
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The Salk vaccine is a major factor in the fight to eradicate polio.
Creamoftartar酒石,aweakacid,canbeaddedtoeggwhitestohelpthemfoam泡沫whentheyarebeaten
With lasers scientists can probe many physical processes, such as combustion, once beyond our ken.视野
Amythical(imaginary)creature,thedragonwasbelievedtohavelion'sclaws,scalyskin,andfierybreath.
Thecontrolsofmostmodernairplanescanbeoperatedeithermanuallyorautomatically.