Dujiangyan is the oldest man­made water system in the world, and a wonder in the development of Chinese science.     1     (build) over 2,200 years ago in what is now Sichuan Province in Southwest China, this amazing engineering     2     (achieve) is still used today.

In ancient times, the region in which Dujiangyan now stands     3     (suffer) from regular floods caused by overflow from the Minjiang River.     4     (help) the victims (受害者) of the flooding, Li Bing, the region governor, together with his son, decided to find a solution. Li designed a series of channels (水渠) built at different levels along mountains that would take away the floodwater while leaving the river flowing naturally.     5     (good) still, the extra water could be directed to the dry Chengdu Plain, making     6     suitable for farming.

Once the system was finished, no more floods occurred and the people were able to live     7     (peaceful). Today, Dujiangyan is admired by scientists around the world because unlike modern dams     8     the water is blocked with a huge wall, Dujiangyan still lets water flow through the Minjiang River naturally,     9     (enable) ecosystem (生态系统) and fish populations to exist     10     harmony.

Filled with     1     (curious), the artist packed his bags and left. When he asked the villagers on the banks of the river where he could find the legendary artist, they smiled and pointed down the river. The next morning he hired a boat and set out     2     (find) the well-known painter. As the small boat moved gently along the river he was left speechless by the mountains being silently reflected in the water. He passed milky white waterfalls and mountains in many shades of blue. And when he saw the mists rising from the river and the soft clouds     3     (surround) the mountain tops, he was reduced to tears. The artist was finally humbled by the greatest artist on earth, Mother Nature.

Grand Canyon National Park recently turned 100 years old. The    1    (nature) wonder in northern Arizona became one of America’s early national parks in 1919. A century later, about 6 million people a year visit the park,    2    is about the size of the state of Delaware.

Native tribes (部落) had many names for the huge canyon. But in 1869,    3    (explore) John Wesley Powell gave it a name that stuck: the Grand Canyon. The canyon isn’t the world’s longest or deepest. But it surely is grand. It offers beautiful views.

The canyon itself is far    4    (old) than the park. No one knows exactly    5     old the canyon is. The rocks    6    the bottom are about 1.8 billion years old.

Humans first came to the area about 12,000 years ago. They left behind a large number of stone tools. For the past century, tools    7    (make) from small sticks    8    (find) in some of the canyon’s caves.

Plenty of animals live in the park. Desert bighorn sheep are    9    largest animals in the Grand Canyon.    10    (measure) 300 pounds, they climb over the rocks. The park is home to almost 375 kinds of birds and a few living things that can be found nowhere else.