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).

Sarek’s mountains used to be covered by vast sheets of ice. Around 9,000 years ago, this ice melted,     1     (leave) behind about 100 glaciers. Soon after, reindeer began to arrive. Following the reindeer were the Sami people, who made this territory their home. Getting here is quite difficult,     2     apart from the Sami very few people have ever seen Sarek. In 1909, Sarek was made a national park in order to keep the land in its natural state. Though the Sami are allowed to continue their traditional way of life in the park, no one else can live here, and all new development     3     (ban) within park boundaries. At the far side of the valley, an ancient Sami cottage is visible. Close by, there are a few reindeer     4     (feed) on grass.

Recycling paper is a great way to help the environment, but reusing things made from paper is even better. Take a copy of magazine, for example. Once you finish     1     (read) it, don’t put it in your recycling bin. Instead, consider sharing it with people     2     haven’t read it, or giving it to your school library so that your classmates can take a look. Maybe, you could find a completely     3     (difference) use for the magazine’s pages. Some readers have used them to wrap gifts for their friends and family.

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.

In ancient times, people held nature in awe (敬畏). For example, the American Indians     1     (believe), “Humans are a part of nature and nature is a part of humans”. However, as human beings master more knowledge, people try to change nature. They use more land     2     (make) buildings and capture some wild animals to suit their own needs. In this process, humans gradually lose contact with nature and even throw it out of balance. Please remember: Nature is not the place to visit. It’s     3     (we) home.