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Natural sources include: .
A、Windblown dust
B、Volcanic ash and gases
C、Smoke and fly ash from forest fires
D、Pollens and other aeroallergens
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A、Windblown dust
B、Volcanic ash and gases
C、Smoke and fly ash from forest fires
D、Pollens and other aeroallergens
A.sources
B.environments
C.origins
D.resources
A.sources
B.resources
C.materials
D.power
A.Resources
B.Sources
C.Materials
D.fuels
A、Windblown dust
B、Volcanic ash and gases
C、Smoke and fly ash from forest fires
D、Pollens and other aeroallergens
Natural sources of radiation are______.
A.radioactive potassium in bones, strontium 90, uranium ore
B.carbon 14 in tissues, cosmic rays, X rays
C.cosmic rays, radioactive potassium in bones, radioactive carbon in tissues
D.X rays, carbon 14, plutonium
A.Y
B.N
C.NG
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