题目内容
1．Scientists in Colombia have trained a team of rats to help remove land mines from the countryside．Land mines are small bombs （炸弹） hidden in the ground and designed to explode when someone steps on them．When trained，the rats can smell special metals in the mines and then signal 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 70rats．
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 695people-56of whom were children．A criminal （犯罪的） 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 come to the rescue．"These rats will be a great help，"he said．
45．How do rats help to find land mines？A
A．By their sense of smell．
B．By their light weight．
C．By their special sight．
D．By their excellent hearing．
46．The advantage of rats over dogs in finding bombs is thatD．
A．they are cleverer
B．they run faster
C．they have a better sense of smell
D．they don't make mines explode as easily
47．The underlined word"They"may refer toC．
A．dogs B．scientists
C．Wistar rats D．Méndez and her team
48．What is the text mainly about？B
A．People in Tanzania are suffering from land mines．
B．Specially-trained rats help clear land mines．
C．Dogs are no longer used to find land mines．
D．Land mines have become a great danger to Colombians．
分析 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．
解答 45．A 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A．
46．D 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．
47．C 词义猜测题．根据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．由此可知，Luisa Fernanda Méndez 和他的团队正在训练Wistar rats，他们是科学家经常用于实验的红色的一种老鼠，结合选项，they应该指的是上文提到的Wistar rats，故选C．
48．B 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B．
点评 本文是科教类阅读理解．做这类题材阅读理解时要求考生对文章通读一遍，做题时结合原文和题目有针对性的找出相关语句进行仔细分析，结合选项选出正确答案．推理判断题也是要在抓住关键句子的基础上合理的分析才能得出正确答案，切忌胡乱猜测，一定要做到有理有据
