Đọc đoạn văn dưới đây và chọn đáp án đúng trong số A, B, C hoặc D. Litter on Mount Everest 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. This 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 can 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. When people begin to climb Mt. Everest, they leave over 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. 1. Where do climbers put their empty oxygen bottles? A. On the ground B. In trash cans C. On their back D. In their tents 2. 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. 3. How much trash is on the mountain? A. Over five hundred kilos B. Over fifteen thousand kilos C. Over five thousand kilos D. Over fifty thousand kilos 4. Why do climbers on Mount Everest carry bottles of oxygen? A. The weather is cold. B. Climbing makes them tired. C. The air is very thin. D. They are thirsty. 5. In line 5, people leave them behind, what does the word “ them” refer to? A. Oxygen bottles B. Tens C. Strong winds D. Other climbers