【全国英语等级考试三级】Unit 3 环境—Passage(3/4)

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Unit 3 Enviroment I 环境
Passage(3/4)
       
Hints:
        York University
         
         
A study from York University, has cast strange new light on the farmers' enemy - foxes. The more foxes a farmer kills, the more lambs he appears to lose to foxes. That is because new foxes will almost certainly occupy the slain animals' territory. And new animals, unused to the terrain, may then choose more obvious prey, such as lambs. The message of studies such as these is that natural systems are complex, unpredictable. Understanding them requires patient observation and careful analysis. The lack of these conditions explains why, in the early modern era, grass sakes were killed as venomous, and gardeners destroyed worms because they were thought to gnaw plant roots.