Back in 1859, an Englishman, Thomas Austin, brought 24 rabbits to Australia's eastern state of Victoria. Never before had there been any rabbits on the Australian continent. Austin and other homesick English settlers thought rabbits would remind them of the green fields of home. They also felt the creatures would provide them with game to hunt.

However, the rabbits spread through Victoria, New South Wales, southern Queensland, and South Australia in no time. Worse, the animals had begun moving west. These little creatures easily went through pastures and crops, and destroyed almost everything in their path. They evicted wallabies(a kind of Australian animal) and other now-endangered animals, moving in and taking over their homes. The rabbits just chose to eat certain grasses and small bushes, which completely changed the local ecosystem. In times of drought, the rabbits dug deep into the ground to find small amounts of water in the roots of plants. As the vegetation cover was destroyed, erosion became a serious problem. By 1894 the threat had reached Western Australia's border.

In the end, a decision was made to build a rabbit-proof fence that would cross the continent from north to south. In late 1901, the construction of the Number 1 Rabbit-proof Fence began. The project required 400 camels, 150 horses, 50 donkeys, and 4 teams of oxen. Posts made of bushes were driven into the ground every twelve feet. Wire netting that reached out three and a half feet above the ground and one foot into the ground was fixed between the posts.

By 1907 the rabbit-proof fence was completed. A second and third fence line had been added when rabbits were found west of the original fence. With the Number 2 and Number 3 fences, Australia was totally divided by 2023 miles of netting. In 1907 the three parts of the rabbit-proof fence made up the longest fence in the world. No one could have imagined the consequences of Thomas Austin's decision to bring rabbits to Australia in 1859. Who could have known what it would take to contain 24 rabbits?

Every day, little Laika searched for food and shelter through the streets and markets. One day, a man was approaching her and held out some food in one hand. Laika sniffed (闻) and slowly crept (爬) towards the treat. Whoosh! Laika was caught in the dogcatcher’s net. She struggled to get free but it was no use. The scientists needed homeless dogs for some tests.

Life in the laboratory was difficult. Machine after machine, the scientists tested how Laika would handle the situation. The scientists liked Laika as she always stayed calm and did whatever they asked her to. Soon, Laika became one of the three dogs considered for a special mission in space. A rocket would be launched in less than a month and there would be a dog on board. No person or animal had been to outer space. Vets and scientists were unsure if it was safe. Dr. Vladimir Yazdovsky recalled that before heading to the launch pad, he took the dog home to play with his children. “I wanted to do something nice for her. I was afraid she had little time left to live.”

In October 1957, the rocket was ready. A special space suit was made just for Laika. The scientists said a teary goodbye and wished Laika good luck. Then, they put her in a tiny cabin in the rocket that was specially set up for her. Soon the engines roared to life. The noise was deafening and Laika’s heart pounded. However, there was no turning back.

A small crowd watched as the gleaming rocket sped up through the sky and out of sight. People across the country cheered for the world’s first true astronaut who carried on such a difficult and dangerous job. This tiny hero paved the way for many human astronauts to come. After a few other flights with dogs, the Soviet Union put the world’s first human—Yuri Gagarin—into space on April 12, 1961.

Walking is the best form of exercise. It is good for the upper respiratory(与呼吸有关的)system and the legs. It helps us control our weight and blood sugar. Walking is also a good way to help you make more friends, bringing chances to see new things and meet new people. Personally I try to walk at least 5 miles daily.

As well as walking, I also cycle around Xiamen. Cycling is great for weight loss and helps to build stamina(耐力). However, cycling does not allow for the same level of social contact as a walk. It is for this reason that I would strongly suggest that you try long-distance walking if you want to be physically healthy. I originally(最初)started walking around Xiamen because I didn’t have a car, but I soon started to enjoy the walking for its own sake.

I have also made many friends during my walks. It’s not uncommon for my 5-mile walk to sometimes take as long as 2 or 3 hours,because I stop to chat with different shop owners along my route. These days, if I skip my walk for even one day, the people in the shops may want to know why I didn’t come.

I’ll never forget the first time some people followed me when I was walking, and asked if it was okay for them to walk with me. I really didn’t know what to say, so I just replied that I didn’t mind. I have been invited for lunch,dinner and sometimes just to sit and drink tea with total strangers. There is nothing more pleasant than walking past a schoolyard and hearing all the kids say hello to me.