Particulates may also be classified by their origin: .
A: Primary—emitted directly from a process
B: Secondary—subsequently formed as a result of a chemical reaction
C: Smoke and fly ash from forest fires
D: Pollens and other aeroallergens
A: Primary—emitted directly from a process
B: Secondary—subsequently formed as a result of a chemical reaction
C: Smoke and fly ash from forest fires
D: Pollens and other aeroallergens
举一反三
- In the fusion reaction of elements formed in the universe, carbon nuclei can be directly generated from helium nuclei. A: 正确 B: 错误
- The 12 years of primary and secondary schooling may also be completed outside the USA.( )
- Which of the following is NOT true? A: Acid rain also damages buildings and railway railings. B: Acid rain kills plants and water animals but is not really harmful to humans. C: Acid rain may attack the regions where it is formed and other regions as well. D: Smoke from factories and power-stations in the USA is the main cause of acid rain in Canada.
- People fly to other places from there.
- Why was an airport forced to close down A: Because the blazes from the fires were too hot. B: Because the smoke from the fires were too thick. C: Because it was too droughty at the airport. D: Because it rained heavily there.