As people turned away from hunting to farming, their life changed. When the food supply became richer and richer, they no longer moved from place to place. The success of their crops depended partly on the weather, but there were also things they could do to help crops grow.

　　In the past, a tribe had to travel many miles for food. Now, only a small amount of land was necessary to feed the whole tribe. The early tribe could grow in size because farming provided a way to feed people.

　　21. Why did the early tribes move so often?

　　A. They enjoyed traveling around.

　　B. They had to find enough food.

　　C. Because of the bad weather they did not like to stay in one place.

　　D. They liked to go hunting everywhere.

　　22. The underlined word "game" in Paragraph 2 probably means "______".

　　A. 游戏 B. 比赛 C. 野味 D. 赌博

　　23. When farming provided enough food to people, ___________.

　　A. the women didn't do any work at all

　　B. the tribe could grow larger and life became steady

　　C. they did not move at all

　　D. they no longer went hunting

　　24. From the passage we can infer that___________.

　　A. early tribes liked moving from place to place

　　B. hunting was interesting in early days

　　C. the change from hunting to farming happened very quickly

　　D. life was hard and unsteady for early tribes

　　Land Art, sometimes referred to as Earth Art or Earthworks, is a form of art which involves using physical landscapes to create art, taking art out of the museum and into the outside world. Modern Land Art movement really got going in the 1960s, when American artists began creating Land Art on a large scale. Today, works of modern Land Art can be seen all over the world, sometimes right alongside much older pieces of Land Art created by people who lived thousands of years ago.

　　Land Art, which is not necessarily unchangeable, can take a number of forms. For example, in 1970 Robert Smithson created the Spiral Jetty(螺旋状防波堤), made of a collection of stones and mud, in the Great Salt Lake. The American artist made a large jetty in a spiral shape which sticks out into the waters of the lake.

　　Reshaping the landscape is a common characteristic of Land Art, which can be created by moving parts around. People can also add things to the environment to create Land Art, like salt, which is added to the Spiral Jetty. It is possible to use plants. In all cases, Land Art is immovable.

　　Land Art is designed to gradually form, change, and eventually decay(衰落). That's one of the biggest differences between Land Art and most of the art one sees in the museums. Some works of art can exist only for a few hours or days. Others are exposed to rain and wind so that they develop and decay over time, which is part of the attractiveness in the eyes of the artists.

　　25. What can be learned from the first paragraph?

　　A. Land Art was the most popular art in the 1960s.

　　B. Land Art aims to get people interested in nature.

　　C. American artists were the first to create Land Art.

　　D. People have been creating Land Art for thousands of years.

　　26. What do we know about Robert Smithson?

　　A. He is a great creative artist.

B. He lives near the Great Salt Lake.