举一反三
- Why does the existence of intermediate state in the 4-level laser can promote the production of laser beam? A: reach population inversion between ground state and metastable state B: reach population inversion between ground state and intermediate state C: reach population inversion between ground state and pumped state D: reach population inversion between intermediate state and metastable state
- When there are two electrons in the N-layer of a ground state atom, The M-layer must have A: 8 electrons B: 10 electrons C: 18 electrons D: 8-18 electrons
- Carbon chains can rotate around a double bond (carbon=carbon or C=C).
- What caused the deposits A: The hydrochloric acid broke the carbon bonds in tile carbon dioxide, B: The magnesium oxide broke the carbon oxygen bonds in the carbon dioxide. C: The burning magnesium broke the carbon oxygen bonds in the carbon dioxide. D: The gas collection method broke the carbon-oxygen bonds in the carbon dioxid
- What caused the deposits A: The hydrochloric acid broke the carbon bonds in tile carbon dioxide, B: The magnesium oxide broke the carbon oxygen bonds in the carbon dioxide. C: The burning magnesium broke the carbon oxygen bonds in the carbon dioxide. D: The gas collection method broke the carbon-oxygen bonds in the carbon dioxide.
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He was severely criticized ________that he didn’t work hard. A: for the ground B: on the ground C: in the ground D: under the ground
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Which of the following statements is true: ( ) A: RO• is not a very reactive species B: RO• is not thought to be an intermediate in the smog-forming process. C: RO• is a free radical D: RO• is readily formed by the action of stable hydrocarbons and ground state NO2
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Which types of discrimination are illegal in the UK? A: Discrimination on ground of sex B: Discrimination on ground of race C: Discrimination on ground of age D: Discrimination on ground of religious beliefs E: Discrimination on ground of sexual orientation
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______ of agricultural practices is a recognized method of carbon sequestration as soil can act as an effective carbon sink offsetting as much as 20% of 2010 carbon dioxide emissions annually.
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The synonym of CO2 is .（ ）。 A: hydrogen B: carbon monoxide C: carbon dioxide D: oxygen