Bài 1 : Cho biểu thức A = -4/n-1 ( với n thuộc Z ) a) Số nguyên n phải có điều kiện gì để A là phân số b) Tìm các số nguyên n để A có giá trị nguyên Bài 2:Cho phân số B =n/n-4 ( với n thuộc Z ) a) Tìm số nguyên n để B là một phân số b) Tìm tất cả các số nguyên n để B có giá trị nguyên Bài 3 :Chứng minh rằng các phân số sau có giá trị là số tự nhiên a) 10 mũ 2011+2/3 b)10 mũ 2010+8/9 Bài 4 : Tìm các số nguyên x ; y biết a) 36/y-2 = 44/77 Mong các bạn giúp mình nhanh mình đag cần gấp

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III. Choose the best answer A, B, C or D to complete these sentences 1. Yesterday, a terrible storm………..the rural area of Ha Giang Province. A. erupted B. struck C. shook D. raged 2. Villagers rushed into public shelters as soon as the volcano………. A. erupted B. struck C. collapsed D. raged 3. Hundred of buildings were completely destroyed when the earthquake………the city. A. buried B. struck C. shook D. raged 4. The mudslide………..the whole village while people were still sleeping in their house. A. buried B. erupted C. shook D. raged 5. The forest fire……….for eight hours and some animals were badly injured or killed A. erupted B. struck C. collapsed D. raged 6. We managed to run out of the house into the street before the walls……….. A. erupted B. struck C. collapsed D. raged 7. The rescue workers set up a camp to provide…………..for the flood victims. A. shelter B. aid C. debris D. forest fire 8. On the second day, there was a rainstorm which helped to put out the………. A. house B. aid C. debris D. forest fire 9. When the storm stared, they took……….in a cave A. shelter B. aid C. debris D. forest fire 10. As the tornado moved through the town, high winds scattered……….across the street. A. house B. aid C. debris D. forest fire IV. Complete these sentences with the suitable words (drought ,flood, hurricane, landslide ,tornado) 1. When there is a ___________, a lot of water covers an area where there usually isn’t water. 2. A ___________ refers to a long time without rain. 3. When there is a ______________, a lot of rocks and earth fall down a hill. 4. A____________ is a storm with a lot of wind that moves over water. 5. A____________ is a storm in which the air moves very quickly in a circle.

1. Construct a sentence from the words given: When/ they/ arrive/ shop/ buy/ fridge/ they/ know/ all/ fridges/ sell. A. When they arrived at the shop to buy a fridge, they knew that all fridges had been sold. B. When they arrived at the shop to buy a fridge, they knew that all fridges have been sold. C. When they arrive at the shop to buy a fridge, they know that all fridges had been sold. D. When they arrived at the shop to buy a fridge, they knew that all fridges had sold. 2. Change the following sentences into Passive voice: Rescue workers had taken local people to a safe place. * A. Local people had taken to a safe place by rescue workers. B. Local people had been taken to a safe place by rescue workers. C. Local people was taken to a safe place by rescue workers. D. Local people took to a safe place by rescue workers. 3. Change the following sentences into Active voice: All of the buildings in my neighbourhood were destroyed by the hurricane. * A. The hurricane was destroyed by all of the buildings in my neighbourhood. B. The hurricane had destroyed all of the buildings in my neighbourhood. C. The hurricane destroyed all of the buildings in my neighbourhood. D. The hurricane destroyed by all of the buildings in my neighbourhood. 4. Rewrite the sentence without changing its original meaning: One way to save the environment is using renewable energy sources. * A. Use renewable energy sources is to save the environment. B. We can save the environment by use renewable energy sources. C. Unless we use renewable energy sources, we will save the environment. D. If we use renewable energy sources, we will save the environment. 5. Combine the two following sentences into a new one that shows a cause/ effect relationship: We can't see the stars at night. There is too much light pollution. * A. Because we can't see the stars at night, there is too much light pollution. B. Due to the light pollution, we can't see the stars at night. C. There is too much light pollution leads to the fact that we can't see the stars at night. D. Since the light pollution, we can't see the stars at night.