Carbon dioxide is like nitrogen in many ways, but if it is mixed with limewater, it causes the clear liquid to because milky, while nitrogen dose not. This is the test for carbon dioxide.

二氧化碳在许多方面类似于氮气，但如果它与石灰水混合，它就使清澈的液体变成乳状液，而氮气不能，由此可以鉴别热氧化碳。

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Test smoke, carbon monoxide and security alarms to make certain they work it’s a good idea to replace batteries even if they are still working.

检查一下烟警报器、二氧化碳警报器和安全警报器，保证其工作正常。 即便是它们现在仍能工作，给它们换换电池也是个不错的主意。

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Alarms. Test smoke, carbon monoxide and security alarms to make certain they work it's a good idea to replace batteries even if they are still working.

警报器。检查一下烟警报器、二氧化碳警报器和安全警报器，保证其工作正常。即便是它们现在仍能工作，给它们换换电池也是个不错的主意。

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The test, called a carbon isotope ratio test, can distinguish naturally produced from artificial testosterone.

NPR: Landis Facing Uphill Battle on Doping Charges

Late Wednesday, his lawyer, Howard Jacobs, acknowledged he'd received a written statement that the carbon isotope test showed the presence of synthetic testosterone.

NPR: Landis Facing Uphill Battle on Doping Charges

Hers is not the lab that did the tests on Floyd Landis, but Dr. Ayotte has used the carbon isotope test since the late 1990s.

NPR: Landis Facing Uphill Battle on Doping Charges