请教prep2-essay2-7

secretsoft

Essay #2. 091 (21422-!-item-!-188;#058&00091-00) More selective than most chemical pesticides in that they ordinarily destroy only unwanted species, biocontrol agents (such as insects, fungi, and viruses) eat, infect, or parasitize targeted plant or animal pests. However, biocontrol agents can negatively affect nontarget species by, for example, competing with them for resources: a biocontrol agent might reduce the benefits conferred by a desirable animal species by consuming a plant on which the animal prefers to lay its eggs. Another example of indirect negative consequences occurred in England when a virus introduced to control rabbits reduced the amount of open ground (because large rabbit populations reduce the ground cover), in turn reducing underground ant nests and triggering the extinction of a blue butterfly
        that had depended on the nests to shelter its offspring. The paucity of known extinctions or disruptions resulting from indirect interactions may reflect not the infrequency of such mishaps but rather the failure to look for or to detect them: most organisms likely to be adversely affected by indirect interactions are of little or no known commercial value and the events linking a biocontrol agent with an adverse effect are often unclear. Moreover, determining the potential risks of biocontrol agents before they are used is difficult, especially when a nonnative agent is introduced, because, unlike a chemical pesticide, a biocontrol agent may adapt in unpredictable ways so that it can feed on or otherwise harm new hosts.
Question #7. 091-06 (21560-!-item-!-188;#058&000091-06)
The passage suggests which of the following about the blue butterfly mentioned in the highlighted text?
(A) The blue butterfly's survival was indirectly dependent on sustaining a rabbit population of a particular size.
(B) The blue butterfly's survival was indirectly dependent on sustaining large amounts of vegetation in its habitat.
(C) The blue butterfly's survival was threatened when the ants began preying on its offspring.
(D) The blue butterfly was infected by the virus that had been intended to control rabbit populations.
(E) The blue butterfly was adversely affected by a biocontrol agent that competed with it for resources.
答案为A.我选E
知道是从原文绿色部分找答案,但不知道答案A 的 indirectly dependent on sustaining a rabbit population of a particular size是怎么推出来的
请大家帮帮忙哈

UMHIVTDC

英格兰引进一种病毒来消灭破坏草皮的一大批兔子，结果同时消灭了蚂蚁窝，而蓝蝴蝶的卵通常产在蚂蚁窝里，这样控制兔子数量就间接影响到蓝蝴蝶的生存。A对。

E是文章没提到的，蓝蝴蝶和生物控制技术并不存在资源竞争的问题。蓝蝴蝶的资源是蚂蚁窝，生物控制技术的资源是草皮。

secretsoft

明白了,谢谢

waytouing

我觉得A这样的解释是错的。我再把A答案key一次。

(A) The blue butterfly's survival was indirectly dependent on

sustaining a rabbit population of a particular size.

你对文章的解读是对的，但是保持兔子的数量并不意味着蚂蚁窝不被消灭啊，是

virus而不是兔子对蚂蚁窝的存在起到作用；或者这样说，科学家又找到一种新方

法，能够消灭兔子之余不消灭蚂蚁窝，那么很显然我们不能说这是indirectly

dependent了。

但是从何种角度对A选项进行解读，现在还是很迷茫。望指导！

callmesoli

为了减少open ground，人们想了个办法去减少了兔子，结果是减少了蚂蚁窝（因为人们使用的消灭兔子的方法：病毒）触发了蓝色蝴蝶的灭绝（文章也介绍了原因，因为蝴蝶要在蚂蚁窝产卵

A说的是蝴蝶的生存并非和兔子的数量的维持，直接相关

对的呀，两者没有直接的关系啊，兔子多，不能得出蓝色蝴蝶多结论

同样，兔子少，也不能得出蓝色蝴蝶少

文章只是说：病毒--》蚂蚁和兔子的同时减少，因为蚂蚁窝的减少，所以蝴蝶才死光了，而并非是因为兔子少了

wyw1018

我的理解
“Another example of indirect negative consequences occurred in England when a virus introduced to control rabbits reduced the amount of open ground (because large rabbit populations reduce the ground cover), in turn reducing underground ant nests and triggering the extinction of a blue butterfly
       that had depended on the nests to shelter its offspring. ”
这个例子blue buterfly是为了说明indirect的影响的问题，
正如楼上所说：
vire引进的目的减少兔子的数量
结果减少了ant nests
ant nest 是buterfly 繁殖后代的地方，进而推出影响了blue buterfly

这就充分体现了indirect 影响

dong870501

自己其实也没有多明白,只是觉得里头的indirect这个词的范围很广,既然indirect了,那么很多的情况便可囊括其中,那么文中的逻辑链(兔子和蝴蝶),是不是能这么觉得——就算是勉强，也能算作是一种indirect?

为何说为勉强,因为这里的逻辑关系只是跟文中提及的这一种特殊的biocontrol agent(virus)有关系,换一种东西,(也许只影响兔子不影响ant),就不会有这样的逻辑链了

xuganwilliam

我的这个题选的是D，能帮我解释一下为什么吗？

Zingales

d 选项， 文章并没有说蓝蝶收到病毒影响。蓝蝶最直接的是受到减少的蚂蚁窝的影响。所以，d是无关选项。