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nguyenngoclinh1990
2 năm trước
Cho phương trình: x²- 2mx + m2 – 4 = 0 a) Tìm m để PT có 2 nghiệm dương phân biệt b) Tìm m để PT có 2 nghiệm âm phân biệt
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VII. Read the following passage, and then tick the correct answers: true (T), or false (F). Most of the world’s energy comes from the sun. The sun’s energy is in wood, oil, and other things that people use for energy. People use many sources of energy. Ancient people used only their arms, hands and simple tools until they discovered fire. Later, people learned to use the energy of the wind to sail ships. Then they learned to use animals to do work. In the 18th and 19th centuries, people began to use machines. The first machines used steam. They burned coal to heat water. The hot water turned into steam, and the steam engine did the work. Later, people began to use the gasoline engine, and today people are using nuclear energy. Energy is one of the basic concepts, or ideas, or physics. It is the ability to do work. Without energy we could not live. We need energy to work, and scientists are always looking for new sources of energy. True False 26. None of the world’s energy comes from the sun. Ao Bo 27. Wind, steam, and gasoline are sources of energy. Ao Bo 28. People have never used nuclear energy. Ao Bo 29. Energy is the ability to do work. Ao Bo 30. We need new sources of energy. Ao Bo

II. Choose the correct answer. 6. Driverless cars have already , and they look so cool. A. gone B. travelled C. exist D. existed 7. If I have a jet pack. I will use to fly anywhere easily. A. my B. mine C. his D. their 8. I think teleportation is only . A. imagine B. imaginary C. imaginable D. imagining 9. Do we need much to park that kind of vehicles? A. land B. ground C. soil D. space 10. Do you think it will be (an) , green way to travel? A. convenient B. inconvenience C. polluting D. polluted 11. I think in the future cities will be more crowded and the traffic will get . A. good B. well C. worse D. wors 12. Which is the best of transport for the future? A. mean B. means C. traffic D. ways 13. Sidewalks are to moving walkways in airports. A. familiar B. similar C. different D. same 14. We are looking for cheap, clean, sources of energy. A. polluting B. harmful C. expensive D. effective 15. We should try to reduce energy as much as possible. A. production B. producers C. consumption D. consumers 16. Solar energy is and it can be replaced easily. A. new B. renew C. renewable D. non-renewable 17. For many people living in rural areas, biogas is a cheap energy available. A. method B. production C. supply D. consumption 18. Sources of energy will be used more for our future. A. effective B. efficient C. effectively D. efficiently 19. regular light bulbs with low energy light bulbs, which use less energy. A. Turn B. Replace C. Place D. Put 20. Don’t forget to the lights when leaving a room or going to bed. A. turn B. turn on C. turn off D. turn out 21. The use of biogas for cooking in the countryside. A. will increase B. will be increasing C. will be increased D. will have 22. The digital camera belongs to Nick. That camera is . A. him B. he C. his D. one 23. Is this schoolbag ? A. you B. your C. yours D. them 24. There are more problems in the slums than in the areas. A. wealth B. richness C. wealthy D. country 25. is quite popular in an overcrowded city where you can see people sleeping in a park or under a bridge. A. Homeless B. The homeless C. Homelessly D. Homelessness

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