The Great Wall of China was built in sections over a period of around 2,000 years, the most famous parts of     1     were built from stone. However, in some areas it was built using “rammed earth (夯土).” This is when soil and rocks are pressed together. Over time, wind and rain can easily wear down rammed earth, so scientists have often questioned how these old sections of the Great Wall     2     (manage) to survive for such a long time.

A group of researchers from China Agricultural University examined     3    370-mile-long section of the wall and found that more than two thirds of it     4     (cover) by biocrust (生物土壤结皮). The scientists took some     5     (sample) of the biocrust back to their lab for testing and discovered that the natural material was     6     (actual) stronger than the rammed earth. Some pieces of the plant-based layer were up     7     three times stronger. This means that the biocrust has strengthened the wall and protected it from     8     (destroy) by weather over the years.

These findings could be important for people who manage ancient structures around the world. Although biocrust may not look     9     (appeal), its natural ability to preserve things could be a very useful tool for experts attempting     10     (protect) precious ancient buildings.

A 5,100-year-old dam, capable of flood control and irrigation (灌溉), has been identified as China’s earliest     1     (know) water engineering project. The Xiongjialing Dam is part of the Qujialing relics site in Jingmen, China’s Hubei Province.

The dam was initially built around 5,100 years ago on a branch of the Qingmudang River. The     2     (exist) dam measures 2 meters in height, 13 meters in width and 180 meters in length. It has a water storage area to the east, equal to the size of three West Lakes, and     3     8.5-hectare irrigation area to the west, with the     4     (late) found to have been an expanse of prehistory rice field. A floodway at the northern side of the water storage area allowed for discharge (排放) of extra water during flood seasons. The dam     5     (construct) with local earth, which was mixed with plant roots     6     (increase) the structure’s toughness.

The design of the water project suggests that prehistoric     7     (ancestor) in the area had learned to control water use rather than     8     (simple) defending against floods and droughts. The Qujialing relics site is famous for witnessing the first-ever discovery     9     carbonized rice along the midstream of the Yangtze River. Researchers say the dam further illustrates that, in the Neolithic Age, the area had a mature rice-growing agriculture. That’s     10     this relies heavily on irrigation.

A flood of tourists, some from overseas, have come to enjoy the unique cultural and natural beauties of the Tibet autonomous region,     1     has witnessed a travel boom recently.

Of the total tourists received, 30,455 were inbound visitors —travelers from overseas —    2     increase of 494 percent year-on-year, while more than 24.21 million were domestic visitors, a 4l percent year-on-year increase.

“    3     impressed me the most was the magnificent Potala Palace and strong     4    (religion) culture in Lhasa.I feel something different from other     5    (place) I visited before,” said Hu Wei, a tourist from Sichuan province.

The Chinese online travel agency Ctrip Group reported that travel order volume, including transportation and hotel bookings, for destinations in Tibet during the first half of the year increased     6     103 percent     7    (compare) with the same period in 2019. The figure reflects a continuous warming trend of tourism in the region.

“It is harder     8    (get) tickets to some hot tourism spots, such as the Potala Palace, as the number of tourists     9    (increase) significantly recently,” said Chodar, a tour guide in Lhasa. “I see large numbers of tourists lined up at the entrance of the palace every day. Visitors have to make a     10    (reserve) at least 10 days in advance.”

In Chinese history, the Yellow River is not just a river; it stands for the origins of culture and civilization. It played     1     important role in the early development of Chinese civilization.

The Chinese refer to the Yellow River as “the Mother River”. That is     2     the Yellow River was the birthplace of ancient Chinese civilizations in the Xia and Shang eras — the richest region in early Chinese history.

Two million years ago, Peking man used     3     (live) in the Yellow River Basin. Moreover, the Chinese regard yellow     4     a color of ancient origins: a symbol of the loess (黄土) land the Yellow River flows through, the emperor, the yellow skin of the Chinese, and the legendary Chinese dragon, from which the Chinese assume     5     (them) to develop.

Confucianism and Taoism were not established until the Zhou Dynasty. Centuries     6     (late),Buddhism (佛教) was successively established there. These three religions spread through the Yellow River area,     7     (keep) a balance between each other. The religious culture in the Yellow River Basin has a much     8     (long) history, however. Actually, a long time ago, the Yellow River valley     9     (give) birth to the most basic form of Chinese religion: worship (崇拜) of ancestors to pray for blessings. Ancestor worship strengthened blood     10     (tie), maintained family identity, and promoted the power struggle in the Yellow River civilization.

In the mountains of southwestern China, widespread karst (喀斯特) landforms have given rise to numerous natural caves,     1     (offer) unique resources for tourism.     2    (equip) with safety facilities and opened to the public in 1985, Zhijin Cave in Guizhou’s Bijie city has emerged as a famed scenic spot. This summer, it has attracted numerous sightseeing tourists and curious students alike, forming large crowds of enthusiastic     3    (visit).

Two weeks ago, more than 100 students and teachers from No. 8 Middle School in Bijie took on an exploration of the cave     4     (learn) about the formation and types of karst caves, as well as ways to protect them. With headlamps on, the students     5     (guide) by interpreters as they ventured into a “karst museum”   where they experienced     6     (extreme) awesome sights. Along the stone steps, they encountered interconnected caves of     7    (variety) sizes and witnessed stalactites(钟乳石)hanging or standing     8     diverse forms.

Study tours are     9     innovative means of linking school education with extracurricular learning. Through the immersive (沉浸式的) learning experiences, the children couldn’t help be amazed at the wonders crafted by nature.   “We have gained knowledge     10     can’t be found in books,” said a student. “Now I know how karst caves were formed.”

Fuxian Lake is the third largest lake in. Yunnan province and is famous for its clean water. It is surrounded by hills on each side, and you can have beautiful views     1    every angle. Last summer vacation, I had the opportunity to enjoy its beauty with my own eyes.

Our first destination was     2    top of the highest mountain where we watched a sunrise. I felt the power of life sweep over me when the sun     3    (rise). As the sun was rising up slowly, the world became brighter. After the sun came out completely, we took quite a few amusing pictures     4    (record) our happy moments. The beauty of nature can     5     (feel) everywhere when we walked along the mountain roads. When it was time to have lunch, we had a picnic under the shade of some trees and appreciated the gift of nature.

After lunch, we went boating on the lake, where I saw many lotus flowers (荷花) blossoming lively.    6     (row) a boat by myself was full of excitement and laughter.

When the sun was setting, we had some local     7     (special) for dinner. I had never had     8    (delicious) dishes than the ones I ate after a whole day’s tour. At night, as we looked at the stars and admired the moon in the deep sky, I felt how small I was in the universe. Yet, at the same time, I knew that it is because of us     9     the world is so beautiful and diverse. The quiet night then brought us into a fairy-tale world full of     10     (innocent), love and fantastic dreams.