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.
According to the passage, which of the following is a concern that arises with biocontrol agents but not with chemical pesticides?
Biocontrol agents are likely to destroy desirable species as well as undesirable ones.
Biocontrol agents are likely to have indirect as well as direct adverse effects on nontarget species.
Biocontrol agents may change in unforeseen ways and thus be able to damage new hosts.
Biocontrol agents may be ineffective in destroying targeted species.
Biocontrol agents may be effective for only a short period of time.
题目分析:
题目释义:
细节题目
考点:
支持主题(Supporting ideas)
旨在考察我们对文章细节的认知
这类的题目定位比较困难,从题设来看,基本定位在全文中间的部分。
选项分析:
A选项:生物控制有可能在毁灭想要消灭的物种的同时也消灭了不想要消灭的物种。从文中的第一句可以看出,生物控制的好处就在于可以消灭特定的物种。也就是说化学制剂可能会消灭掉其它不应该被消灭的物种。后文有提到说,生物控制也可能会对其它物种产生影响。所以,这点不是两者的不同点。
B选项:生物控制有可能用直接的和非直接的影响在非目标生物上。从文中可以看出,生物控制不能直接影响非目标生物。第一句就阐明了生物控制不会影响其它生物,但是后文阐述了会有非直接的影响。
C选项: Correct. 生物控制可能会有不可预见性的改变并且有能力毁掉新的物种。这个选项定位在“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.”。几乎是原文的直译。
D选项:生物控制也许会对想要消灭的物种无效。文中没有讨论消灭目标物种的有效性问题。
E选项:生物控制也许只在一段时间内有效。文中没有提到生物控制是否长期有效。
biocontrol agents “more selective than most chemical pesticides” 生物方法比化学方法更具选择性
(biocontrol agents) selective (than most chemical pesticides) in that they ordinarily destroy only unwanted species 生物方法只摧毁固定的不想要的物种,they指的是biocontrol
但后文说biocontrol有潜在影响,所以其实二者都对其他物种有影响,故A错误
🐎一下
A:文章第一句“和chemical相比,生物控制只会destroy unwanted物种”,因此A选项错误
B:生物控制会对untarget物种有非直接的影响,但是没有直接影响(也就是直接的destroy),所以排除
a biocontrol agent may adapt in unpredictable ways, so that it can feed on or otherwise harm new hosts.
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.
they指代对象是biocontrol agents
More selective than most chemical pesticides in that they ordinarily destroy only unwanted species, biocontrol agents eat, infect, or parasitize targeted plant or animal pests. 主语是bio,bio more selsective than chemical
A 选项:文章第一段的第一句话
A:文章第一句“和chemical相比,生物控制只会destroy unwanted物种”,因此A选项错误
B:生物控制会对untarget物种有非直接的影响,但是没有直接影响(也就是直接的destroy),所以排除
这个问题难在如何把问题表达的意思同文章内容联系起来
问题问的是同B同时出现但不与P同时出现的担心
这个问题的第二个难点在于无法通过题目直接定位原文
①根据题目的一部分信息排除无关答案:不与P同时出现→由此可以排除A,B
②对于短篇文章可以读完全文,根据有关无关性排除D,E。
but not with chemical pesticides, 看完题目就开始找ba特有但是其他化学杀虫剂没有的选项,但是找着找着,就把其他化学剂没有的这个点给忘了,这种情况不是第一次出现了,如何避免
new hosts 新的物种
感觉定位在最后一句: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.
unpredictable = unforeseen;
it can feed on or harm new hosts=able to damage new hosts
在阅读里问个语法题……文章第一句
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. 这个they是指前面的chemical pesticides还是后面的biocontrol agents呢? 按照语法来说应该是前者吧……
这个语法上也是指biocontrol agents。in that的主语和前面相同,而前一个句子more selective的主语应该是biocontrol agents
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