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标题: prep07 第17题 [打印本页]

作者: PMFTOTC 时间: 2013-10-2 01:02
标题: prep07 第17题

17. (27669-!-item-!-188;#058&003302)

Urban air contains more sulfur dioxide than does rural air, and plants in cities typically grow more slowly than do plants in rural areas. In an experiment to see how much of the difference in growth is due to sulfur dioxide, classes in an urban and a rural school grew plants in greenhouses at their schools and filtered the greenhouse air to eliminate sulfur dioxide. Plants in the urban greenhouse grew more slowly than those in the rural greenhouse.

Which of the following, if true, would it be most important to take into account in evaluating the result?

(A) The urban school was located in a part of the city in which levels of sulfur dioxide in the air were usually far lower than is typical for urban areas.
(B) At both schools, the plants in the greenhouses grew much more quickly than did plants planted outdoors in plots near the greenhouses.
(C) The urban class conducting the experiment was larger than the rural class conducting the experiment.
(D) Heavy vehicular traffic such as is found in cities constantly deposits grime on greenhouse windows, reducing the amount of light that reaches the plants inside.
(E) Because of the higher levels of sulfur dioxide in the air at the urban school, the air filters for the urban school's greenhouse were changed more frequently than were those at the rural school.

这道题我没太懂，不是说要看how much of the difference in growth is due to sulfur dioxide么？那做实验应该一个用sulfur dioxide一个不用作对比么. 为什么这里两个一个农村一个城市都用 filtered the greenhouse air to eliminate sulfur dioxide
都filter了还比什么呀？？？？

作者: PMFTOTC 时间: 2013-10-2 22:29
求解答！！

作者: 拧发条喵 时间: 2013-10-2 23:00

PMFTOTC 发表于 2013-10-2 22:29
求解答！！

现实中城市和农场SD条件不同，为了检验SD是不是真正原因，消除SD因素以后看结果是否发生变化，
不好理解么？
说通俗一点就是有两个MM，A漂亮 B不那么漂亮，LZ更喜欢漂亮的那个
为了证明LZ不是因为外表才喜欢人家，你可以说，就算A和B长着同一张脸，你还是更喜欢A

作者: PMFTOTC 时间: 2013-10-2 23:07

拧发条喵发表于 2013-10-2 23:00
现实中城市和农场SD条件不同，为了检验SD是不是真正原因，消除SD因素以后看结果是否发生变化，
不好理解 ...

你的类比好难懂。。。。
哎。。。我太笨了

作者: 拧发条喵 时间: 2013-10-3 00:01

PMFTOTC 发表于 2013-10-2 23:07
你的类比好难懂。。。。
哎。。。我太笨了

刘亦菲和凤姐，LZ爱刘亦菲
我说，LZ你就是觉得刘亦菲比凤姐好看才喜欢刘亦菲的
你说，就算刘亦菲长凤姐那样你还是爱她!

= =行了嘛

作者: frauschirm 时间: 2013-10-3 04:55
先要排除sulfur dioxide以外所有的因素，才能确定sulfur dioxide是唯一影响树木生长速度的唯一因素。
anyway这个题目其实是找个原因能解释文中提到的现象就好。

作者: 女娲丁丁丁 时间: 2013-10-3 15:18
答案是什么

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