5 Air is a mixture of oxygen, nitrogen and other gases.Which statement explains why oxygen can be separated from nitrogen by the fractional distillation of liquid air? D A Oxygen is denser than nitrogen. B Oxygen is more reactive than nitrogen. C The two elements have fixed melting points....
A. Because there are larger populations in cities. B. Because the air in the city is dirty. C. Because there are much more gas fumes from cars and burning of coal and oil for energy in the city than in the country. D. I答案]C 相关知识点: 试题...
A.the cause of air pollution is people B.the causes and the effects of air pollution are both found in cities C.the effects of air pollution range from headaches to death 2. What is the purpose of this passage 2 A.to persuade people to stop polluting the air B.to tell the causes of...
BEIJING, Feb. 25 (Xinhua) -- Despite China's repeated explanation that the entry of a Chinese civilian unmanned airship into U.S. airspace was an entirely unintended, unexpected and isolated event caused by force majeure, the United States, without any evidence, slandered the airship as a ...
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3. Check if the infrared sensing photoelectric sensor is not aligned with the reflector or if the photoelectric switch is damaged. Just replace it with a new one. As long as the system prompts and personnel arrangements are followed when using the air shower room, users can quickly complete ...
19.Endless Journeyisreally a wonderful film. I’ve never seen ___ one like it. A. better B. a better C. best D. the best 20. Which of the following words is a compoundword like “wartime”? A. impatient B.schoolwork C. German D. carelessness 21. — Why...
9. What is the woman’s suggestion? A. Going to the city center. B. Taking a short cut home. C. Meeting Jim in the park. 听第8段材料,回答第10至13题。 10. What did Clara do at the weekend? A. She planted vegetables. B. She went to a yard sale. C. She visited her grandpa...
CNET named theM3 MacBook Airthe overallbest laptop of 2024. This model has a stunning 13.6-inch Liquid Retina display, an 18-hour battery life and 8GB of RAM. It's also designed to work withApple Intelligence. The basic 256GB configuration is currently sold out, but you can upgrade to ...