If a sixth mass extinction occurs, scientists who have studied the issue believe that up to three quarters of all species on Earth could die out. Of course, as we humans depend on so many species for our survival, we would also be at risk of     1    (die)out. Our world and our lives depend on the balance in nature     2     animals and plants. Without forests, we would have no air, and without clean water we would be unable     3    (survive).

Saving nature is at the very heart of what we do as World Wildlife Fund (WWF). We protect wildlife for many reasons. It is a source of inspiration. It boosts a sense of wonder. It is fundamental (重要的) to the balance of nature. In our work, WWF     1     (focus) on saving populations of the most important species in the wild.     2     (final), by protecting species, we save this beautiful and irreplaceable planet     3     is called home.

An animal that has not lived in Australia for over 3,000 years is back. The creature is Tasmanian devil (袋獾). Conservation groups     1       (release) 26 Tasmanian devils in a large natural reserve north of Sydney. The Tasmanian devil is the size of a small dog. It feeds     2     large birds and household waste. It has been an     3       (endanger) species for decades since Australian wild dogs wiped them out on the mainland. The devil gets its name from its high-pitched sound and the fierce way in     4     it fights for food. Although its name sounds so scary, experts say it is not a danger to humans.

The conservation group Aussie Ark worked with other animal protection     5     (organise) on the project to release the Tasmanian devils. The animals are in a natural reserve to help keep their chances of survival high. They     6     (leave) to find their own food and survive by themselves ever since. Tim Faulkner, president of Aussie Ark, told National Geographic, “They are free. They’re out there. We’ve got some basic methods of keeping an eye on them, but     7     (actual), now it’s time for the devils to do what they do.” He was     8     (hope) about the future of the devils,     9     (say) “This release of devils will be the first of many. We are talking about something monumental,     10     true landmark in history.”

Every year, more than 13 billion plastic bottles are sold in Britain. All of them     1     (use) only once, and only half of them are recycled.

Some think plastic bottles should be banned(明令禁止).     2     think they should be recycled. Others think a returning plan should be brought in to avoid the     3     (pollute) of rivers and seas. That is to say, people will get up to 20 pence back every time they return     4     bottle. A returning plan for bottles is already     5     (success) in Germany, where 98.5% of plastic bottles are returned.

    6     (lucky), there are already signs that things are changing for the better. Last year, Selfridges stopped     7     (sell) single-use water bottles. London Zoo announced that it would also ban them. It sold 155,000 plastic bottles of water last year. Now it will sell only reusable plastic bottles,     8     can be filled by visitors from taps. Families visiting beaches this summer are being asked to take part in a plan called “Return To Offender”. The idea is     9     (post) plastic bottles and other litter they find back to the     10     (company) that made them, using their freepost addresses.

The United Nations want everyone to know that the world is in danger. They hope that the governments will act     1     (quick) in order to conserve nature. Here is one example of the problem. At one time there were 1300 different plants, trees and flowers in Holland,     2     now only 860 remain. The others have been destroyed by modern man and his technology. We are changing the earth, the air and the water, and everything     3     grows and lives. We can’t live     4     these things. If we continue     5     (treat) the earth like this, we shall destroy     6     (us).            

What will happen in the future? Perhaps it is more     7     (significance) to ask “What must we do now?” The people who will be living in the world of tomorrow are the young of today. A lot of them know that     8     (conserve) is necessary. Many are hoping to save our world. They plant trees, build bridges across rivers in forests and so on. Lately in a small town in the United States the banks of eleven kilometres of a river     9     (clean) by a large group of girls. Young people may hear something about protecting the earth through a record     10     (call) “No, One’s Going to Change our World”, which was made by Scatles, Cliff Richard and other singers. The money from it will help to conserve wild animals.

Another example is a 2011 proposal for a tall "Birdscraper" building in New York. The building is intended     1    (protect) birds and fight pollution at the same time. It would be in the middle of a lake, birds would sit on it, and their droppings would fall into the water. The droppings would feed water plants    2    would then create oxygen through photosynthesis(光合作用).

If we learn to share our space, we can become better neighbours to the wildlife around us. If we do not, more species will become extinct and our own future will     3    (endanger).