[求助]prep1-17

crystalgan

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.

答案为D

E为什么不对呢？

wandola

其实mm只要小心读懂题目意思就好了。

D的意思大概是说，城市里灰尘太多沉淀在温室玻璃表面，减少了可以到达PLANT的阳光。--〉光和作用少了...

E说的是什么城市空气中二氧化硫的浓度太高，城市学校里面温室里用来过滤SO2的过滤器必须要经常更换（比乡下学校里面的）..

这样说来e与植物生长没有必然的关系。

crystalgan

哦，明白了 谢谢啦

djvivid

B错在什么地方？

B说在温室中的植物（包括市区和郊区里的）比户外的植物（也包括市区和郊区里的）都长得快，并且题目中已说温室里过滤了SO2,所以说明SO2的确是影响植物生长。

djvivid

期待nn的解答

djvivid

up

gracetin

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(此次實驗目的是要了解sulfur dioxide對植物生長影響), 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?

本題探討的重心在Plants in the urban greenhouse grew more slowly than those in the rural greenhouse.

=>皆生長在greenhouse(即排除sulfur dioxide)但是為何urban和rural生長結果仍不相同(實驗結果)

(因為根據實驗的目的在排除sulfur dioxide後兩者的生長需要相同，此實驗設計才可說明sulfur dioxide對植物生長的影響)

=>評價實驗結果：尋找可造成此結果的他因(因為若是沒有他因存在則表示sulfur dioxide對植物生長無影響)

根據此想法

(D)提供了其他原因導致生長差異說明了實驗結果

(B) 基本上算是無關選項

因為此選項我們可以知道greenhouse(或sulfur dioxide)對生長的確有影響

但是無法解釋Plants in the urban greenhouse grew more slowly than those in the rural greenhouse. 所以對這次的實驗結果
            完全起不到解釋作用

EricMIT

楼上解释的很好。

说实话，这题我开始也错选B。终于想清楚了，希望对同选B的战友们有所帮助：

选B是因为自己想设计一套办法来验证文章开头的陈述：二氧化硫影响植物生长；而实际上这道题目后来笔锋一转（狡猾啊！），重点已经不在这了。重点在最后，出现了城市和农村都排除了二氧化硫的影响后，植物生长还是不一样，问为何？

这样D选项很好的解释了这一原因。也就是正确答案了。

个人认为，这道题目最好别当一道Evaluate的题目做，想清楚后，应该是一道“explain why”的题型；

当然evaluating the result在这里基本上就是explaining the result的意思。

seafly_diao

...

[此贴子已经被作者于2009/8/30 11:16:57编辑过]

mandy4

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…… 这个实验的要求是验证Urban 和 Rural 在growth 上的不同 due to sulfer.

D选项做到了要求的对照组：Urban plants 和 Rural plants.变量是grime on greenhouse windows,而把变量sulfer去掉了，如一位NN所说：
"这里的result是在滤去sulfur dioxide的rural 和 urban greenhouse里面 urban 植物还是长的慢

这是个对照实验 说明sulfur dioxide已经不是造成这个现象的原因 所以只能是它因,也就是D-different amount of light"

验证了在due to sulfer方面，U&R plants growth没有不同。

而B选项，设置了两组四个对照，分别是Urban inside&Urban outside 和 Rural inside&Rural outside.只能分别验证由于sulfer不同造成的，城里的室内外growth以及乡下的室内外growth有什么不同，城里乡下之间并没有直接对比，直接对比的是各自的室内外的情况。因而B不对。