新概念英语第四册第17课:A man-made disease

Lesson 17   A man-made disease人为的疾病      First listen and then answer the following question.      听录音，然后回答以下问题。      What factor helped to spread the disease of myxomatosis?        In the early days of the settlement of Australia, enterprising settlers unwisely introduced the European rabbit. This rabbit had no natural enemies in the Antipodes, so that it multiplied with that promiscuous abandon characteristic of rabbits. It overran a whole continent. It caused devastation by burrowing and by devouring the herbage which might have maintained millions of sheep and cattle. Scientists discovered that this particular variety of rabbit (and apparently no other animal) was susceptible to a fatal virus disease, myxomatosis. By infecting animals and letting them loose in the burrows, local epidemics of this disease could be created. Later it was found that there was a type of mosquito which acted as the carrier of this disease and passed it on to the rabbits. So while the rest of the world was trying to get rid of mosquitoes, Australia was encouraging this one. It effectively spread the disease all over the continent and drastically reduced the rabbit population. It later became apparent that rabbits were developing a degree of resistance to this disease, so that the rabbit population was unlikely to be completely exterminated. There were hopes, however, that the problem of the rabbit would become manageable.      在澳大利亚移民初期，一些有创业精神的移民不明智地把欧洲兔子引进了澳大利亚。这种兔子在澳大利亚及新西兰没有天敌，因此便以兔子所特有的杂乱交配迅猛繁 殖起来。整个澳洲兔子成灾。它们在地下打洞，吃掉本可以饲养数百万头牛羊的牧草，给澳洲大陆造成了毁灭性的破坏。科学家们发现，这种特殊品种的兔子（显然 不包括别的动物）易患一种叫“多发性粘液瘤”的致命毒性疾病