The Salk vaccine is a major factor in the fight to eradicate polio.
A、completelydestroyA
暂无解析
Batsfly,ratherthanglide,andthusaretheonlymammalscapableoftrueflight.
TheSalkvaccineisamajorfactorinthefighttoeradicatepolio.
People who do not sleep enough tend to become irritable .
Thecontrolsofmostmodernairplanescanbeoperatedeithermanuallyorautomatically.
The controls of most modern airplanes can be operated either manually or automatically.
