Orang-utan live deep in the jungle of South-East Asia. For years, they were a complete mystery to humans. Hunters sometimes saw these shy animals from a distance, but rarely got a good look at them. No one was certain whether they were a race of humans or a kind of monkey. Indeed, the name ”orang-utan“ means ”man of the forest“. Finally, about 150 years ago, scientists confirmed that orang-utans were a(n) 【小题1】of ape. Since then, people have been able to come into increased contact with orang-utans. Consequently, we have learnt much about them.

While the 【小题2】of civilization has brought us more knowledge about orang-utan, it has caused the orang-utan many problems, and now these wonderful creatures are threatened with extinction. In 1900, there were several hundred thousand orang-utans living in the wild. Now there are fewer than 24,000 【小题3】in the world. Some experts even believe that orang-utans will become extinct by the year 2023.

Humans are 【小题4】to blame for this decline. Altogether, 80% of the orang-utan’s natural habitats has been destroyed by companies cutting down trees for financial 【小题5】. Another problem is the trade in orang-utan babies. Every year, thousands of these babies are 【小题6】to other countries, where they serve as zoo animals or as pets. Unfortunately, to 【小题7】an orang-utan baby, its mother must be killed as well.

In order to save the orang-utan, many 【小题8】centres have been set up to preserve their natural habitats. Governments and volunteers are also working to rescue pet orang-utans and return them to the wild. However, this may be too little, too late. The existence of orang-utans is at a 【小题9】stage. People must take 【小题10】action if orang-utans are to survive in the future.

Boyan Slat has one huge goal. It’s a goal that could be good for people and animals all over the world. 【小题1】, it looks like he’s going to meet his goal.

When he was 16. Dutch engineering student Slat was on vacation in Greece, and he started to think about all the rubbish that is pushed onto beaches by water. The oceans around the world are all of plastic—millions of tons of plastic. 【小题2】, plastic doesn’t just disappear. It takes centuries to break down.

The present 【小题3】 of the oceans is bad and worrying, and Slat wanted to do something to change it. So he made it a personal goal to clean up the rubbish in the world’s oceans.

Slat started with an idea for an unusual machine to “catch” the plastic floating(漂浮)in the water using the 【小题4】 energy of the ocean. He left school in 2013 to begin work 【小题5】 his project The Ocean Cleanup. Soon, the project received a lot of attention.

A year later, Slat was named a “Champion of the Earth” by the United Nations for his valuable work.

Rain forests, found in Earth's temperate and tropical zones, are some of the most biologically varied ecosystems on the planet. All rain forests share certain【小题1】, including a closed canopy,     the dense vegetation of the top branches that forms a roof above the forest floor, a damp and warm climate, and【小题2】 constant   temperatures throughout the   year. Most of   the forest's insect   and   animal life grows well in the canopy's leafy and sunlit environment. The forest's ground cover, by comparison, is small. Less than 2 percent of the sun's light makes its way through the canopy and the darkness below. This darkness, along with the poor quality of the soils,【小题3】plant growth.

Rain forests are a(n)【小题4】 part of   Earth's   total   ecology.   Huge   amounts   of   water are absorbed into tree roots and【小题5】into   the atmosphere   from the   tree leaves through   a process called transpiration（蒸发）. Tree roots also fix the soil in place and slow the runoff of rains into rivers and oceans. Through the process of photosynthesis（光合作用）, rain forests absorb more carbon dioxide and give off more oxygen than any other ecosystem.

The rain forests are【小题6】shrinking at a rapid rate as a result of the profitable ventures of farming, logging, and mining. When tropical rain forests are【小题7】in order   to raise cattle and     crops, the nutrient-poor soils are quickly【小题8】. When farmers move on to new areas heavy rains and baking sun leave the land fruitless and lifeless. Logging and mining cause similar damage to the land and destroy the territory of【小题9】 millions of birds, insects and animals. By some 【小题10】an area of tropical rain forest the size of the state of Delaware disappears in this way every month.