Scientists in Colombia have trained a team of rats to help remove land mines from the countryside. Land mines are small bombs hidden in the ground and designed to explode(爆炸) when someone steps on them.
When trained, the rats can smell special metals in the mines and then signal(发信号) to their human team. Then why use rats for such an important job?
In the past, dogs have been used to find bombs. Rats have a good sense of smell and can respond to orders, just like dogs do. But rats are much lighter than dogs. They stand less of a chance of setting off the mines, which explode under a certain amount of weight. What’s more, the best rats are cheaper to keep than dogs. It costs about the same amount of money to take care of one dog as it does 70 rats.
The rats have already been used in Tanzania, an African country with many land mines. Luisa Fernanda Méndez and her team in Colombia are training the even lighter Wistar rats. These are the white rats with red eyes that scientists often use in laboratory experiments. “They even train their babies to perform their jobs, which saves us a lot of time, ” Méndez said.
Colombia has the second-highest rate(比率) of deaths from land mine accidents in the world. Last year, land mines killed 695 people — 56 of whom were children. A criminal group called the Revolutionary Armed Forces of Colombia, or FARC, as well as other organizations, have placed the mines. FARC are strongly against Colombia’s government. The group has placed mines all around its own bases and in many places in the countryside.
In the past, the Colombian government hired peasants and poor farmers to find mines. Many of them died trying to find the well-hidden bombs.
Colombian police official Erick Guzmán hopes the team of rats can e to the rescue(援救). “These rats will be a great help,” he said.
【小题1】How do rats help to find land mines?A．By their special sight. B．By their light weight.C．By their sense of smell.D．By their excellent hearing.【小题2】The advantage of rats over dogs in finding bombs is that .A．they are cleverer.B．they run fasterC．they have a better sense of smellD．they don’t make mines explode as easily【小题3】The underlined word “They” may refer to .A．scientistsB．Wistar ratsC．dogsD．Méndez and her team【小题4】 What is the passage mainly about?A．Specially-trained rats help clear land mines.B．People in Tanzania are suffering from land mines.C．Dogs are no longer used to find land mines.D．Land mines have bee a great danger to Colombians.C
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(答案→)C
解析：本文叙述了科学家们在哥伦比亚已经训练一组老鼠帮助在农村清除地雷。以前用狗来帮助清除地雷，老鼠的优势他有灵敏的嗅觉，能够闻出特殊的金属味，并且他们的体重轻引爆地雷的可能性小，还有养它们的费用比养狗的费用低。
【小题1】细节理解题。根据the rats can smell special metals in the mines and then signal(发信号) to their human team.老鼠可以闻到特殊的金属在煤矿,然后给人发信号，故选C。
【小题2】细节理解题。根据But rats are much lighter than dogs. They stand less of a chance
of setting off the mines,但是老鼠比狗更轻。他们的体重轻引爆地雷的可能性小，故选D。
【小题3】词义猜测题。根据The rats have already been used in Tanzania, an African country with many land mines. Luisa Fernanda Méndez and her team in Colombia are training the even lighter Wistar rats. These are the white rats with red eyes that scientists often use in laboratory experiments.上文提到的是Wistar rats ，故选B。
【小题4】主旨大意题。根据全文的内容主要说的是受过特殊训练老鼠帮助清理地雷，故选A。