Every year, about 1.6 million tons of soil flows into the Yellow River, China's    1    (two)longest river. The soil contains materials to keep the    2    (nature)balance of the area. Over time, a lot of soil has been removed,    3    has caused serious erosion(侵蚀)of the land along the river. In some areas in Shanxi Province, this has destroyed almost all the land,    4    (force)many local farmers to move to other areas.

It is a huge job to control the Yellow River erosion. Usually many people believe the best work    5    (do)by government or international organizations. You may agree to this point of view. If so, it is time for you    6    (think)again.

In fact, it is you that play the most important role    7    stopping the Yellow River erosion. Did you know the    8    (important)of your 5 yuan? For a start, it can buy you a tree, which will help make soil stay on the land. On land with rich soil, local farmers can grow crops to make    9    living, and with the money they earn from    10    (they)crops, farmers can buy goods or services. All of these help to develop local economies.

Polar bears live in such environment that is too cold for most animals. For much of the year, they live and hunt on the     1     (freeze) Arctic sea ice. Nature has prepared them for the cold conditions but nothing has prepared them for the danger     2     threatens their only home.

Polar bears’ world is melting. Polar bears     3     (suffer) in a warmer world are in danger. Studies show that the polar ice     4     (reduce) by 9.8% every ten years since 1978. At present, about 20,000 to 25,000 polar bears live in the Arctic. Polar bears depend on the sea ice for their     5     (survive). “The sea ice is more than just the platform that the bears walk     6    .” says Andrew Derocker, who studies North American polar bear population. “Without it, they can’t exist.”

Some melting and refreezing of the polar ice is nature. But in     7     warmer world, these cycles speed up, and bears have     8     (little) to hunt.     9     (normal), they have three months in the spring when they gain more weight and the extra fat     10     (use)   later, when the bears are not actively hunting. Therefore, it’s urgent to protect the environment and maintain the ecological balance.

Trash is a big problem. You do your part to reduce, reuse and recycle it.     1     is it enough?

I do my part to recycle things and bring my bags for purchases, but I am far     2     producing zero waste. Recently a family of four in California talked about their zero — waste lifestyle on a television show which     3     (great) inspired me to some extent. The family live in a wealthy country. While     4     (raise) two children, Bea Johnson, the hostess     5     (determine) to live a zero ---waste lifestyle since then.

Her children just pack their     6     (lunch) in bags which they can reuse the next day. They have simplified their lives so completely that they are able to pack up easily and spend     7    (extend) periods of time travelling and doing things they love. They are able to pay for the trips because they spend 40%     8     (little) on living expenses. They also rent their home while they are gone and give detailed instructions to the renters on     9     they can create a zero-waste lifestyle.

I'm happy about the achievement that they have gained; meanwhile I     10     (encourage) by their example to do more in the future.