The first UN Chinese Language Day at the United Nations     1     (observe) on Friday at UN Headquarters in New York in 2010.    2     the world’s most widely spoken language, it seems appropriate that Mandarin (普通话) has one day every year dedicated (把……专用于) to it. This     3     (official) marked day of Mandarin language celebration was set by the United Nations as a way of celebrating the language’s history and     4     (contribute) to the world. It is hoped that having one day every year     5     (celebrate) Mandarin will encourage more people around the world to take it up. With China likely to become the     6     (large) economy in the world, it is important that the wider world becomes interestingly more perfect in this wonderful language. Every year UN Chinese Language Day     7     (fall) on April 20.A great way to get     8     (involve) in the celebration is to join a Mandarin class or attend one of the many Confucius Institutes (孔子学院)     9     are set up by China in countries around the world. The number of people learning Chinese is on     10     increase in China’s neighboring countries, such as Korea, Japan, and Vietnam.

The Xi'an City Wall is     1     most complete city wall that has survived China's long history. It     2     （build）at first to protect the city in the Tang dynasty and has now been completely restored（修复）. It is possible     3     （walk）or bike the entire 14 kilometers.

We accessed the wall through the South Gate. The wall is 12 meters in     4     （high）here you can see streams of people     5     （move）inside and outside the City Wall.

After spending some time looking at all the defensive equipment at the wall, we decided it was time for some action and what     6     （good）than to ride on a piece of history!

We     7     （hire）our bikes from the rental place at the South Gate. My bike was old and shaky but did the job. It took us about 3 hours to go all the way     8     the Xi'an City Wall. Supposedly you can do it in two hours, but we stopped at the different     9     （gate）and watchtowers to take pictures or just to watch the local people going about their     10     （day）activities.

Formed in 2001, the China International Search and Rescue Team ( CISAR ) brings help and hope to those     1     lives are changed by natural disasters.

The team went     2     its first international rescue mission (使命) in 2003. It was the first time that a Chinese team had worked outside China, and the team won high praise for their     3     (brave) and skills. The list of people to whom help has been given ever since     4     (be) long. The team treated more than 3,000 people who were injured in the 2006 earthquake in Indonesia, and spent several months     5     (give) aid to over 25,000 victims (受害者）of the 2010 floods in Pakistan.

Rescue workers     6     (train) to find people, treat the injured, and hand out food, water, and other supplies. There is     7     (usual) no electricity or water after a disaster and diseases and accidents may appear.     8     (save) lives, rescue workers have to work day and night, and sadly they must also bury     9     dead, which means they have to be strong in both the body and the mind. Rescue workers must have big hearts, too. Of course, they’ll have to take     10     (effect) measures in action. The members of the CISAR are always ready to go wherever help is needed.

The earth is the only planet that scientists are certain has life. What does the earth have that the other planets don’t? For one thing, the earth has just the right temperature. As     1     third planet from the sun, the earth seems to be just the right distance away. The planets that are closer to the sun are     2    (extreme) hot and their surfaces are baking in the sun. The farthest planets are cold balls.

When the earth developed, it     3     (cover) by many gases. The gases caused the earth     4     (become) hot. But something amazing happened. The temperature was just right for thick clouds to form. It rained very hard     5     a very long time . This gave the earth its oceans. Water made     6     possible for plants to grow. Then the plants created oxygen in the atmosphere which is the gas that humans and     7    (animal) breathe.

Mars (火星) is the only planet in the solar system     8    seems to be something like the earth. It is smaller than the earth and it is quite a bit     9    (cool) than the earth. But it is not too cold for humans. The most unexpected sight on Mars is dried-up river beds. It is believed that Mars was once much wetter. Does this mean there could have been living things on Mars? Scientists are not sure, but there     10    (be) no sign so far.

By the Shang Dynasty (around 1600-1046 BCE), these symbols     1     (become) a well-developed writing system. Over the years, the system developed into different forms, as it was a time     2     people were divided geographically,     3     (lead) to many varieties of dialects and characters. This,     4    , changed under Emperor Qinshihuang of the Qin Dynasty (221-207 BCE).

People need transportation to move from one place to another. As time went by, transportation methods improved. Especially after the invention of airplanes, they made travel more convenient and     1     (easy).

The airplane     2     (invent) by Orville and Wilbur Wright in 1903.     3     first airplane, Wright Flyer I, flew 36.5 meters in 12 seconds. After that, the two brothers kept     4     (improve) their airplanes. They     5     (fly) in public in France in 1908, and started taking passengers with them. From then on, many other people made great efforts to improve and develop airplanes. Thanks to their efforts, airplane technology developed     6     (extreme) fast.

Today, airplanes have many different     7     (apply). People can use airplanes to travel to other countries, send urgent mails and help people in danger. They use airplanes to send water, food, medicine, etc. to cities     8     urgent (紧急的）help is needed. However, airplanes are not only used in positive ways,     9     they are also used to fight wars.

Many things     10     (change) since the invention of the airplane. Airplanes have made travel or transport faster. Airplanes have really changed our lives.