5、In the African country of Tanzania, a company from Belgium called APOPO trains African giant pouched rats(非洲巨袋鼠) to find dangerous land mines(地雷)left over from wars. The rats are trained to smell out some of the chemicals in the mines. After 8-12 months of training, the rat can find mines so they can be safely destroyed.

       Trained dogs often perform this important work, but APOPO director Bart Weetjens recently discovered that the African giant pouched rat costs far less money to train and care for. These rats may seem huge. Their bodies are 12 to16 inches long, not including their tails. But their size suits the job: At one and a half to 3 pounds, they are too light to set off the land mines.

       Rats and trainers search one small area at a time. When a rat smells mines, it lets the trainers know by pawing(用爪子抓)at the dirt in that spot. The trainers mark each spot on a map. Later, technicians explode the mines safely. In the African country of Mozambique, nearly half the population is younger than 15 years old. A lot of kids are in danger as they play or work.

       “In the town of Vilanculos, children had been playing on the football field, until there was an accident,” Bart Weetjens said. APOPO rats and trainers helped other organizations make the area safe. “The football field has been opened again, and there is no danger any more,” Weetjens said.

       About 80 million land mines are buried out of sight in more than 60 countries around the world. As APOPO’s program grows, the rat heroes might travel the globe!

1．The underlined word “they” (Para. 1) refers to_____.

       A．the trainers                     B．the mines                C．the wars                 D．the rats

2．Why are rats chosen to be trained to find the land mines?

       A．They are native to Africa                      B．They are smarter than dogs

       C．They are cheap to keep and train           D．They are quick to escape from danger

3．What is the task of the rats in the job?

       A．To mark a map                                    B．To find the mines

       C．To set off the mines                             D．To paw at the ground

4．What happened on the football field in Vilanculos?

       A．A land mine exploded                           B．A player was injured during the training

       C．The children were attracted by the rats  D．The villagers tried to get the field back