Papermaking technology is one of the four great     1     (invention) in ancient China. Before it was invented, the Chinese people carved or     2    (write) characters on tortoise shells, animal bones, bamboo slices, wooden plates or thin tough silk. Tortoise shells, animal bones and wooden plates were too heavy to use while silk was too expensive.

Till the Eastern Han Dynasty an official named Cai Lun created a kind of paper,    3     (use) bark (树皮) along with old fishnets, rags and hemp waste.     4     paper was suitable for writing and was also very cheap, so it became very popular. Therefore, Cai Lun’s contribution    5     the papermaking was great.

After the Eastern Han Dynasty, the papermaking technology was gradually improved. And then other materials such as bamboo and straw could also be used to make paper. Due to different material various types of paper were produced for different uses. For example, the Xuan paper     6    (make) in Xuanzhou of Anhui Province belonged to the high-quality paper     7    (special) adapted for use in Chinese calligraphy (书法) and painting.

Later, the technology     8    (introduce) to many countries. The invention of paper provides a more     9    (convenience) way for the storage and communication of information,    10     it also has great significance on the development of global civilization.

Up to now, an autonomous underwater vehicle (AUV) developed by a Chinese university team has obtained abundant data during the country's latest Arctic expedition,     1     (reveal) various features beneath the North Pole.

The red, fish-shaped robot called “XH1000” was made by researchers from Harbin Engineering University. During the 13th Arctic Ocean scientific expedition     2     concluded in late September, it     3     (complete) under-ice environment detection operations near the Chukchi Sea and relayed plenty of data, including ocean water temperature, salinity and pH levels.     4     (equip) with domestically developed detection sonar (声呐), the polar-observing AUV explored an area of 7, 000 square meters beneath the Arctic ice.

Operation team leader Zhu Zhongben,     5     associate professor, said the     6     (inform) gathered will help scientists improve their understanding of the changing process of sea-ice and ocean currents in this region, providing data support for     7     (effective) coping with the impact of global climate change     8     China.

Chinese scientists set off for the 13th Arctic Ocean scientific expedition on July 12 aboard the polar icebreaker Xuelong 2, travelling 15, 000 nautical miles before returning. It reached the North Pole on Sept. 5, generating     9     (value) experience for robotic ships     10     (work) in the high risk polar areas and filling the gap in the country's scientific research on the polar region.

Hey, everyone! It’s Kai again. I’m back with another     1     (amaze) episode of NatGeo kids. And this week we’re talking all about robots. Okay so I bet you’re wondering     2     exactly is a robot. Good question.    3     (basic), a robot is a machine    4     (create) to perform a series of actions. These actions could be as simple as rolling around the house vacuuming out dirty floors. Other robots perform more complicated tasks such as traveling to and     5     (explore) different planets like NASA’s Mars exploration Rovers which were built    6     (study) the surface of Mars. And did you know that humans have been building robots for    7     (century)? In fact many believe the first robot was created over 2,000 years ago. A man called Artistas in ancient Greece     8     (build)a bird-like self-propelling machine that could fly up to a distance of 200 meters that’s like two football fields. Today robots come    9     all shapes and sizes. Some are small even microscopic while others are large in some cases as big as a car or even a truck.

There are flying robots, robots that can drive and robots that can swim, robots that can do a lot of things. Who knows, maybe one day robots will be able to do just about everything    10     humans can do.