You may think there is only sand in the desert (沙漠) of the world, _________ it is not true. In the desert, as we know, there is a little _________, but it is not _________ for most plants. Still we can see some plants live in the desert.

There is _________ in some places in the desert. We call these places oases (绿洲). In the oases, there are villages and towns. People grow all kinds of crops in the fields there.

People _________ live around the oases. They have camels, sheep and other animals. These animals depend on the desert plants for their food and do not need _________ water.

The animals are useful to the desert people in many ways. They eat the meat and drink the milk of the animals. They use the camel for carrying water, food, tents and something else.

The people of the desert have to keep moving from place to place. They must always _________ grass or desert plants for their animals. When there is no more food for animals, _________ move to another place. The desert people are _________. No man in the desert would ever __________ to help the people in trouble and give them food and water.

In 1834, the clock tower in London was burned down. People planned to build a new clock which would be the biggest and best in the world. The clock had to be big and keep very good time. The big clock was made in two years. Five more years later the tower was finished. Then people put the big clock in the tower, and made it ring out for the first time on July 11,1859.

In order to give the big clock a good name, people held a meeting. Someone wanted to call it the Queen of Bells, and someone thought Victoria was good. At last, a man named Benjamin Hall stood up. He was a big man. Before he started to speak, someone shouted, "Why not call it Big Ben?". Everybody laughed and agreed with him.

From then on, Big Ben became its name. And it also became a famous building of London. People all over the world write to Big Ben. They even send birthday presents, bottles of oil to help keep Big Ben running. Big Ben is not only a clock but also a dear friend of people.

Paris, France

New changes have taken place in Paris in recent years. Paris used to be among Europe's busiest cities. Traffic jams could be seen all the time. But now there is a new2.5 kilometre-long car-free area inside the city. The Louvre（卢浮宫）attracts world tourists.   

People visit there not just for the art works, but also enjoy the roof（顶部）of the building which is like a flying carpet. The world's most beautiful city is now even more beautiful.

Lijiang River National Park, China

Lijiang River is in Guilin. It is well-known for its clear water, limestone（石灰岩洞）and green hills. The hills have beautiful names depending on different shapes, such as "Elephant Trunk". These attract many Chinese poets and artists. The best way to enjoy Lijiang River is to take an 83km boat trip from Guilin to Yangshuo in summer.

Zurich, Switzerland

What do you think Zurich is famous for? Great banks? Yes. People can find many Swiss banks and foreign banks here. But the city is of great interest to many people for another reason. Zurich hosts Europe's largest street party each year. Its Street Parade has overtaken（超越）London's Notting Hill Carival. What's hot in the city in 2021?In August, Zurich will host the European Athletic Championships. This gives tourists a chance to see the world's top athletes making new records.

Adelaide, Australia

Many people may know Sydney or Melbourne. They are big cities in Australia. But Adelaide wins people's hearts with great festivals and tasty food. Adelaide Fringe Festival is the largest art festival in Australia. Every February and March, people celebrate with outdoor art works, dance performances and live music. Adelaide has many kinds of foreign foods. British fish and chips, Italian pizza and German pork can be found in most restaurants.

Dubai is a city of big business, expensive hotels, skyscrapers（摩天楼）, and shopping malls. In the early 20th century, Dubai was a successful trading port（贸易港）. People from the world stopped in Dubai to do business. But it was still a small city, and most people lived as fishermen and businessmen. Then in 1966, oil was discovered. This brought a lot of money into the area, and soon Dubai began to change.

Today Dubai is one of the world's most important business centers. In fact, each year the city gets its money mainly from business, not oil.

These years more and more visitors around the world come to Dubai. They come to relax on its beaches, and every year, millions visitors just to go shopping!

Dubai is also one of the world's fastest growing cities. Many tall buildings are built in months. The city also has many man-made islands. One of these, the Palm Jumeirah, is like a palm tree （棕桐树） and is very beautiful.

The city is still an excellent mix of people from different countries. The people from 150 countries live and work in Dubai, and foreigners now outnumber Dubai natives（本地人）by eight to one!

Many people welcome the city's growth. But a lot of Dubai natives worry about the speed of change. As a Dubai native says," We must always remember where we came from. Our kids must know we worked very very hard to get where we are now, and there's a lot more work to do."

A national park is an area that is protected by the government of a country. Every country in the world has a number of national parks. National parks are built to protect the natural environment, in which the local plants and animals live and grow. They also protect certain landscapes（风景）, which are of special importance for a place or for a country.

National parks are important to us for many reasons. One of which is that they help protect wildlife. We share our planet with many kinds of plants and animals. They can live for a longer period of time when their living places are protected. Moreover, there are many kinds of plants and animals that are really rare（稀少的）and cannot live at all if they are taken out of their natural living places. In such cases, their populations often go down, so they are in danger of going extinct（灭绝的）. National parks help protect such rare and native kinds.

National parks are protected areas that often have beautiful landscapes such as snow-covered mountains, sandy beaches and foggy rainforests. They may be worse if they experience more human interference（ 干涉 ）. Luckily, a national park is a good pollution-free environment with less human interference. This helps to protect the landscapes.

What's more, national parks provide a much healthier environment for us. Here, plants make fresh air, and the waterways are also clean. Therefore, walking in national parks, people may find some peace of mind.

The Great Wall in China is k    76     to people all over the world. It is called the Ten-Thousand-Li Great Wall in Chinese. Do you know the famous Chinese saying "He who does not reach the Great Wall is n    77     a true man."?

The Great Wall is the l    78     wall in the world. It is m    79     than 6,000 kilometres long, and b    80     four and five metres wide. In most places it is wide enough for five horses or ten m    81     to walk side by side along the top. It was very difficult to build such a great wall w    82     our modern machines. All the work had to be done by hand. Many people were made to work on the wall away from t    83     homes. Thousands of them d    84     and were buried（埋葬） under the wall. The Great Wall was made not only of stone and earth, but also of the flesh and blood（血肉）of m    85     of men.

86. 假设你是王平，请你给你的英国笔友Harry写一封E-mail，向他介绍你最喜欢的一条小河的情况。内容包括以下要点：

Yours,

Wang Ping