Mount Everest is the highest mountain and 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 oxygen bottles; 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 enough energy to go down the mountain safely with these things. Trash is a terrible problem. Since people first began to climb Mt. Everest, they have left 50,000kilos 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.

26. 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

27. Where do climbers put their empty oxygen bottles?

A. On the ground                                 B. In trash can

C. On their back                                  D. In their tent

28. Why do climbers leave their trash on the mountain?

A. Special group will pick it up.

B. They don’t have enough energy to take it away.

C. The wind will blow it away.

D. Other climbers will use it later.

29. Why do climbers on Mt. Everest carry bottles of oxygen?

A. They are thirsty.                           B. The weather is cold.

C. The air is very thin.                      D. Climbing makes them exhausted.

30. What does the word “them” in line 5 refer to?

A. tents

B. oxygen bottles

C. strong winds

D. other climbers