At 8,844.43 meters high, Mount Qomolangma is     1     (tall) mountain on Earth. While     2     is famous for its challenging hike, parts of the mountain are facing a problem: garbage. Every year, thousands of     3     (visit) throw away tons of trash, including soda cans (罐) and plastic bags.

According to the UN, over 140 tons of trash have been left on the mountain. To reduce trash, China is limiting the number of people     4     can climb the mountain’s north side. Only 300 people will     5     (allow) to climb it each year, and only during spring.

Local residents cleaned the mountain last year,     6     (remove) trash at a height of 5,200 meters. They     7     (collect) about 8.4 metric tons of trash, according to figures from the Tibet autonomous region’s government (西藏自治区人民政府).

This year, the local government plans to spend 4 million yuan       8    a new clean-up campaign, setting up stations to sort, recycle and break down garbage collected from the mountain.

In addition to trash, workers will also collect the bodies of     9     (die)   climbers. As of the 2019 climbing season, more than 300 people have died on Qomolangma, with 12 deaths this year.

A group of artists will try to turn some trash into artwork. They will show these works     10     (local), to remind people not to leave trash when climbing the mountain.

With the     1     (develop) of industry, air pollution is getting more and more serious. In Beijing, many people suffer different kinds of illnesses because     2     air pollution.

Air pollution is caused by the following     3     (factor): about half of the problem is caused by vehicles. There are more and more cars, buses on the roads, and they give off     4     (poison) gases. 25% of air pollution is caused by factories. Another factor is the smokers. Smoking not only does harm to their health     5     to others.     6     these, about 10% of air pollution is caused by other reasons. We should take some measures to fight     7     pollution. New fuel can be used to take     8     place of gas. We can plant more trees. If everybody realizes the     9     (important) of environment and does something to stop pollution, the problem will     10     (solve).

I was one of the people     1     work on Qinghai-Tibet Railway, which was completed by overcoming the most difficult engineering challenges to protect the delicate ecosystem.     2    (allow) animals to move safely and freely, thirty-three     3    (passage) have been built. To prevent damage to wetlands and grasslands, 675 bridges, which is about 160 kilometers in     4    (long), were built and 140,000 square meters of wetlands     5    (move) to protect its distinct ecosystem. Tanggula Station, which     6    (locate) at over 5,000 meters above sea level, is the highest railway station in the world. To keep us     7    (health), several oxygen-making stations were constructed. To protect Cuona Lake     8     construction waste, a twenty-kilometre wall was built. Thanks to     9     efforts, passengers, who have been attracted by the Qinghai-Tibet Plateau, have been enjoying these     10    (impress) landscape.