一道新题. 能解释一下原因吗

Agricultural economist: We can increase agricultural production without reducing biodiversity, but only if we abandon conventional agriculture. Thus, if we choose to sustain economic growth, which requires increasing agricultural production, we should radically modify agricultural techniques.

Which one of the following principles, if valid, most helps to justify the agricultural economist's reasoning?

A) Agricultural production should be reduced if doing so would increase biodiveristy
B) Economic growth should not be pursued at the expense of a loss of biodiveristy
C) Economic growth should be sustained only as long as agricultural production continues to increase
D) Preserving biodiveristy is no more important than increasing agricultural production
E) Agricultural techniques should be radically modified only if doing so would further the extent to which we can increase agricultural production.

D？

What is the key?

楼上兄弟，又碰到了。呵呵

这道题我选C。

前提 abandon conventional agriculture=radically modify agricultural techniques,是一个东西。你可以说不是，但那是assumption题。without reducing biodiversity和题设无关，是干扰。

逻辑分析

1。increase agricultural production-> abandon conventional agriculture

2。increase agricultural production is NECESSARY BUT NOT SUFFICIENT to sustain economic growth,

结论

3。 sustain economic growth->radically modify agricultural techniques

从这里可以看出，要推出结论，这里面有个GAP，就是2里面所说的，"require" is only necessary but not sufficient。所以，要补上这个GAP，就需要，

sustain economic growth->increase agricultural production

而这正是C里面所说的。

我认为应该选B。

hehe, sensornet兄讲的有理！

兄弟我看到C时，as long as的意思没翻译对，所以还以为是无关项

这道题是道没有正确答案的讨论题. 但看了别的论坛上的讨论,都同意B.我仔细考虑一下觉得B应该是正确答案.

cause: abandon conventional agriculture ------> increase agricultural production without reducing biodiversity

reasoning:  should radically modify agricultural techniques ------> increase agricultural production ,---> sustain economic growth

increase agricultural production 可以有很多方法,为什么should modify agricultural techniques? 因为前面原因中已经提到,only if we abandon conventional agriculture 才可以increase without reducing biodiversity.

the reasoning 其实默认了 sustain economic growth 要考虑保持diversity.

所以应该选　　B) Economic growth should not be pursued at the expense of a loss of biodiveristy

不知道我有没有说清楚．

hi, sensornet,glad to see you again. 这道题我还是从那个论坛上找到的．

A only if B 的逻辑关系是 A->B,

A if B 的逻辑关系是 B->A。

所以你看你的cause里面的逻辑关系，好像是反了。所以你的结论可能不对。

请看下面的链接。我做这道题的时侯就觉得跟那道题很象。

http://forum.chasedream.com/dispbbs.asp?boardID=24&ID=17359&page=1