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标题: [求助]老管的一道题，请帮忙解释。谢了。另外谁有划分前提、结论的秘诀，总搞不清楚。 [打印本页]

作者: Tiger99 时间: 2005-12-12 16:24
标题: [求助]老管的一道题，请帮忙解释。谢了。另外谁有划分前提、结论的秘诀，总搞不清楚。

Two centuries ago, Tufe Peninsula became separated form the mainland, isolating on the newly formed Tufe Island a population of Turfil sunflowers. This population’s descendants grow to be, on average, 40 centimeters shorter than Turfil sunflowers found on the mainland. Tufe Island is significantly drier than Tufe Peninsula was. So the current average height of Tufe’s Turfil sunflowers is undoubtedly at least partially attributable to changes in Tufe’s environmental conditions.

Which of the following is an assumption on which the argument depends?

There are no types of vegetation on Tufe Island that are known to benefit from dry conditions.

There were about as many Turfil sunflowers on Tufe Peninsula two centuries ago as there are on Tufe Island today.

The mainland’s environment has not changed in ways that have resulted in Turfil sunflowers on the mainland growing to be 40 centimeters taller than they did two centuries ago.

The soil on Tufe Island, unlike that on the mainland, lacks important nutrients that help Turfil sunflowers survive and grow tall in a dry environment.

The 40-centimeter height difference between the Turfil sunflowers on Tufe Island and those on the mainland is the only difference between the two populations.

作者: hestia 时间: 2005-12-12 18:28

结论是：现在的高度差别至少部分因为T岛的环境变化。

问假设

c.The mainland’s environment has not changed in ways that have resulted in Turfil sunflowers on the mainland growing to be 40 centimeters taller than they did two centuries ago.

c排除他因

把c取非,大陆的环境变了，致使大陆的Turfil sunflowers比200年前长高了40厘米（而不是岛上的变矮了40厘米）

也就是说高度差不是因为岛上的环境变化，起削弱作用

讨论过：

[URL= http://forum.chasedream.com/dispbbs.asp?BoardID=24&ID=88990] http://forum.chasedream.com/dispbbs.asp?BoardID=24&ID=88990[/URL]

作者: Tiger99 时间: 2005-12-12 21:27

谢谢了！明白

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