Read the following passage, and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions. Mount Everest is the highest mountain in the world. It is also the highest trash pile in the world. About 400 people try to reach the top every year. Having many climbers means a lot of trash. It is very dangerous to climb Mt.Everest. The air is very thin and cold. Most people carry bottles of oxygen; they could die without it. When the oxygen bottles are empty, people throw them on the ground. When strong winds rip their tents, people leave them behind. They don‟t have the energy to take the trash away. They only have enough energy to go down the mountain safely. Trash is a terrible problem. Since people first began to climb Mt.Everest, they have left 50, 000 kilos of trash on the mountain. Several groups have climbed the mountain just to pick up the trash. When people plan to climb the mountain, they have to plan to take away their trash. 27. What is the main topic of the passage? A. Wind on the mountain B. A problem with trash C. A dangerous mountain D. Climbing safely 28. Why do climbers leave their trash on the mountain? A. Special groups will pick it up. B. The wind will blow it away. C. They don‟t have the energy to take it away. D. Other climbers will use it later. 29. Why do climbers on Mount Everest carry bottles of oxygen? A. The weather is not cold. B. Climbing makes them tired. C. The air is very thin. D. They are thirsty. 30. What does the word them refer to? A. tents B. oxygen bottles C. strong winds D. people