C
In 1879, a group of explorers made an incredible find. They discovered paintings of remarkable beauty on the walls of a cave in Spain. Some scientists believed that these paintings were created by early humans from the Stone Age, between ten and thirty thousand years ago. Other scientists and the public did not believe the claim, but over the years, it was proven correct. Our ancestors had incredible artistic talents.
Most of the cave art that has been discovered has been found in Spain and France. A smaller number of such caves are located in Italy, Portugal, Russia, and other countries. Scientists believe that many more caves will be discovered in the coming years, and are concentrating their efforts on Africa and the area between Europe and Asia. These two regions of the world were, populated first by humans.
Cave art was carved or painted on the walls and roofs of caves, usually near the entrance. The entrance area was probably chosen to take advantage of daylight and to allow many people to view the paintings. In some cases, the art appears much deeper in caves and requires artificial light. Evidence suggests that the artists used torches or shallow bowls in which animal fat was burned.
9.What was the response of general public to the discovery of cave art made by Stone Age people?
A. They believed it at first.
B. They did not believe it.
C. They thought it was beautiful.
D. They ignored it.
10.According to the passage, what can we conclude about animal fat?
A. It does not burn.
B. Stone Age artists used it to preserve their paintings.
C. It can be burned to produce light.
D. Stone Age artists mixed it with their food.
11.. Where do scientists expect to find more cave paintings?
A. In Central and South America.
B. In Spain and France.
C. In the places where there are caves with large openings.
D. In the regions of the world first populated by humans.
12.Where would this passage be most likely to appear?
A. In a textbook about early human history.
B. In a textbook about modern art.
C. In a dictionary.
D. In an encyclopedia entry about caves.
，因为粒子比荷相同，所以运动时间相同，即ta=tb，根据几何关系可知从c点射出的粒子转过的圆心角较小，则运动时间也较短，所以ta=tb＞tc，故A正确B错误