托福official15综合写作生物学类Integrated Writing范文+题目解析

The cane toad won't be as easy to get rid of as the reading suggests. The measures proposed by the reading are likely either to be unsuccessful or to cause unwanted environmental damage.First of all, a national fence probably won't stop the spread of the toad. That's because young toads and toad eggs are found in rivers and streams. No matter where the fence is located, at some point there will be rivers or streams flowing from one side to the other. These waterways will be able to carry the young toads and their eggs to the other side. Since it's only necessary for a few young toads or eggs to get through the fence in order to establish population on the other side, the fence is unlikely to be effective.Secondly, a massive group of volunteers could have success trapping and destroying toads. But it's likely that these untrained volunteers would inadvertently destroy many of Australia's native frogs. Some of which are endangered. It's not always easy to tell the cane toad apart from native frogs especially when it's young.Third, using the virus is a bad idea because it could have terrible consequences for cane toads in their original habitat in Central and South America. You might be wondering: how can a virus released in Australia cause harm in the Americas? Well, Australian reptiles and amphibians are often transported to other continents by researchers or pet collectors for example. Once the animals infected by the virus reach Central and South America, the virus will attack the native cane toads and devastate their populations. That would be and ecological disaster because in the America cane toads are a native species and a vital part of the ecosystem. So if they are eliminated, the whole ecosystem will suffer.