Between 121 BC and 111 BC, Emperor Wu set up four counties to the west of the Yellow River, Jiuquan, Wuwei, Zhangye and Dunhuang 【小题1】 (expand) the influence of the Han central government and develop ties with countries in XiYu (西域), 【小题2】 were west of the Yumen Pass in today’s Central Asia. As a result, the national postal system of the Han Dynasty, 【小题3】 (act) like a network of blood vessels, expanded to help improve the communication between the central government 【小题4】 the grassroots ones on its northwestern border.

The postal system of the Han Dynasty consisted 【小题5】 three tiers— ting, you, and zhi. Tings were usually set up every two and a half kilometers, providing 【小题6】 place for passengers and envoys (使节) to rest on their journey. The distance between two yous was around 15 kilometers, the longest distance a man could cover by foot in a day. A zhi was the 【小题7】 (big) post station, set up at a distance of 40 kilometers, the one a horse-drawn carriage could reach in a day.

According to the records, sitting on the Hexi Corridor that connected ancient China and XiYu countries, Xuanquanzhi, the post house 【小题8】 (function) for more than 400 years as a hub (枢纽) that delivered mail and 【小题9】 (office) documents, as well as hosting envoys and foreign guests. “The Xuanquanzhi Ruins was a beautiful knot on Silk Road,” 【小题10】 (proud) said Zhang Defang, founding director of the Gansu Jiandu Museum.

For centuries, people dreamed about leaving Earth and travelling to other worlds. Then, in 1957, the Soviet Union 【小题1】（make） the first small step into space 【小题2】 sending up a small satellite called Sputnik.

Early space activities were conducted 【小题3】（main） by the United States and the Soviet Union. But as time went by, Europe and Japan also learned how to build 【小题4】（they）own satellites and rockets. Today, countries such as China, India, South Korea, Israel and Brazil are also developing space industries.

During the last 60 years, unmanned probes（探测器）have been sent towards many of the planets 【小题5】（exist） in the Solar System. Many space observatories, such as the Hubble Space Telescope, have been created to look at the 【小题6】（distance） universe. They have sent back some amazing pictures taken in visible（可见的）light. And they can also observe stars that are invisible to human eyes. The flood of 【小题7】（discovery）has changed the way we look at the universe.

More than 500 people have flown in space since Yuri Gagarin paved the way in 1961. 20 people have travelled to the moon, 12 of 【小题8】 have walked on the moon. So far, space stations   【小题9】（build）, and astronauts have learned to live and work in space for many months 【小题10】   even years.

The classical gardens of Suzhou, Jiangsu Province date back to the 6th century 【小题1】 the city was founded 【小题2】 the capital of the Wu Kingdom. Today, more than 50 of these gardens are still in 【小题3】 (exist), nine of which are regarded as the finest embodiments (化身) of Chinese “Mountain and Water” gardens.

Built in the 11th century on the site of an 【小题4】 (early) destroyed garden, Canglang Pavilion has the longest history among all the existing classical gardens in Suzhou. Naturally 【小题5】 (lay) out and well designed, it is called one of the four best gardens in Suzhou. The garden looks simple but natural. Without complex decorations, it combines buildings with scenery so well 【小题6】 the whole garden appears to be naturally created. Since many of the 【小题7】 (origin) features of the garden have been preserved, the garden has a high historical and artistic value.

The classical gardens of Suzhou 【小题8】 (be) the most vivid specimens (样本) of culture from the East Yangtze Delta region in the 11th to 19th centuries. The underlying philosophy, literature, art, and craftsmanship 【小题9】 (show) in the architecture, gardening as well as the handcrafts perfectly reflect the monumental 【小题10】 (achieve) of the social, cultural, scientific, and technological developments of this period.