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Everybody loves to hate invasive species. The international list of invasive species—defined as those that were introduced by humans to new places, and then __41__ — runs to over 4,000. In Australia and New Zealand hot war is fought against introduced creatures like cane toads (蔗蟾蜍) and rats. Some things that are uncontroversial (无争议的) are nonetheless foolish. With a few important exceptions, campaigns to __42__ invasive species are merely a waste of money and effort — for reasons that are partly practical and partly philosophical. Start with the practical arguments. Most invasive species are neither terribly successful nor very__43__. Britons think themselves surrounded by foreign plants. __44__, Britain’s invasive plants are not widespread, not spreading especially quickly, and often less of a(n) __45__ than vigorous native plants. The arrival of new species almost always __46__ biological diversity (多样性) in a region; in many cases, a flood of newcomers drives no native species to extinction. One reason is that invaders tend to colonise __47__ habitats like polluted lakes and post-industrial wasteland, where little else lives. They are nature’s opportunists. The philosophical reason for starting war on the invaders is also __48__. Elimination campaigns tend to be __49__ by the belief that it is possible to restore balance to nature — to return woods and lakes to the state before human __50__. That is misguided. Nature is an everlasting mess, with species constantly emerging, withdrawing and hybridizing (杂交). Humans have only quickened these processes. Going back to ancient habitats is becoming __51__ in any case, because of man-made climate change. Taking on the invaders is a(n) __52__ gesture, not a means to an achievable end. | 
