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thuhien26082005
2 năm trước
1) Số nguyên x thỏa mãn: |x + 2| = |x - 2| 2) Với x,y là số nguyên thì | x - y | - |y - x| = .... 3) Tìm 2 số nguyên a; b( a > b) biết a/b= -2/5 và BCNN(|a|;|b|)=100. Tìm a,b
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IV. Read the passage and circle the correct answer. Light pollution Most of us are familiar with air, water, and land pollution, but did you know that light can also be a pollutant? Not many people know about this kind of pollution. Light pollution is the inappropriate or excessive use of artificial light and it can have serious environmental consequences for humans, wildlife, and our climate. Light pollution is a side effect of industrial civilization. Its sources include building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminates sporting venues. The fact is that much outdoor lighting used at night is inefficient, overly bright and, in many cases, completely unnecessary. This light, and the electricity used to create it, is being wasted by spilling into the sky, rather than focusing on the actual objects and areas that people want illuminated. For three billion years, life on Earth in a rhythm of light and dark that was created solely by the illumination of the Sun, Moon, and Stars. Now, artificial lights overpower the darkness and our cities glow at night. It disrupts the natural day-night pattern and shifts the delicate balance of our environment. Light pollution has negative impacts. It increases energy consumption, disrupts the ecosystem and wildlife and harms human health. Fortunately, concern about light pollution is rising dramatically. A growing number of sciences, homeowners, environmental groups and civic leaders are taking actions to restore the natural night. 1. What source of light does not contribute to light pollution? A. moonlight B. streetlight C. offices D. advertising 2. What is NOT true about light pollution according to the passage? A. People are so familiar with it. B. Is has many bad effects on humans and the environment. C. It is the inappropriate or excessive use of natural light. D. It is a side effect of industrial civilization. 3. What disrupts the natural day-night pattern as mentioned in the passage? A. artificial light B. darkness C. our city D. night 4. Which is NOT mentioned as the negative impact of light pollution? A. increasing the use of energy B. disrupting the ecosystem. C. badly affect human health D. balancing the ecosystem

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