题目内容：

In 1940, four teenage boys and their dog were walking through woodland close to Lascaux, when their dog suddenly disappeared. The boys searched all around. They came to a cave and looked into the cave 1. could see nothing.

A few days later, the boys returned to the cave. They could hardly believe 2. eyes. In the weak lamplight, the boys saw red horses and cows, and black bulls and deer charging across the walls of the cave, which looked so 3. (frighten) that the boys jumped back in fear. Little did the boys know that they had made one of the most important 4. (discover) of that century.

The Famous Lascaux Caves consist of a large hole and 5. series of connecting caves, with a natural water system. The paintings there were an especially important find because they are so numerous and so well preserved. After a few years, the caves were opened 6. a tourist attraction, and 1,200 people per day came to the site 7. (admire) the paintings.8. (fortunate), many visitors resulted in changes in the cave’s atmosphere, and green algae (水藻) began to grow around the walls. Since then, the caves 9. (close) to the public in an effort to conserve the fragile paintings in this precious underground site.

Today, the caves have computer-controlled air-conditioning and are inspected daily. Scientists hope that these precautions will prevent any 10. (far) damage to the paintings.