Qomolangma is the world's highest mountain. You may have learned from your textbooks that its height is 8,844.43 meters. But not all sides are in agreement on this. Different researchers have given different results. In addition, the height of the mountain can change over time.

That's why a Chinese survey team with over 30 members set out to reach the peak of Qomolangma to re­measure its height on May 6, 2020. They were equipped (配备) with the latest technology.

It is not an easy task. The average air temperature on the mountain is ­-29℃, and powerful winds blow all the time. In such bad conditions, surveying drones (无人机) cannot work at the peak of the mountain. That's why it's still necessary to send human experts to the peak to get exact results.

But does a difference of a few meters really matter when it comes to a high mountain?

In fact, measuring the height of Qomolangma is about more than just getting one exact number. Mount Qomolangma is at the point where the Eurasian plate (欧亚板块) meets the Indian plate. It formed 38 million years ago as the two plates hit each other. Changes in the peak's height can show whether the two plates are heading toward or away from each other. This can help us understand the movement of the earth's crust (地壳).

The survey team will also get first­hand information about environmental conditions at the top of the mountain. This will help us understand how climate change has affected the Qinghai­Tibet Plateau (高原).

Buildings around us are of great value to us. We need houses to keep     31     warm and we build stadiums to watch football matches and museums to keep beautiful things in.

Many people work together on a building. The architect (建筑师) decides how the building is going to look.     32     make sure the building will be strong and safe. Then, the workers     33     build it.

The Sydney Opera House is a famous     34     building with a lovely roof. But it is beautiful from every side, not only from the top. There is also a famous roof on the Olympic Stadium in Munich. The interesting building looks     35     a tent that is made of glass.

Tigers live in many places around the world. They live in the forests and they feed on meat. But they are in danger. There are few tigers     36     in the wild. There are many reasons for this. First, people cut down so many trees that tigers     37     enough places to live. People cut down trees in order to make paper, build houses and so on. Second, people kill tigers to get the fur of them to make money.

What can we do to protect tigers? First, we should     38     money to set up nature parks. Then tigers are going to have safe places to live. Second, the government should develop plans     39     after them. Third, we can't cut down too many trees or kill tigers anymore. We can hand out notices to ask people not to do it. What's more, there are scientists doing research to help tigers     40     more babies.

It's sad to think of tigers in danger. We need to protect them better.