GWD25-Q 13 to 15:

Grassland songbirds often nest in the same grassland-wetland complexes as waterfowl, particularly in a certain

part of those complexes, namely, (5) upland habitats surrounding wetlands.Although some wildlife management procedures directed at waterfowl, such as habitat enhancement or restoration, may also benefit songbirds , the impact(10) of others, especially the control of waterfowl predators, remains difficult to predict.

虽然对waterfowl的一些措施可以使songbird收益,但是对其他生活的影响,尤其是对waterfowl predators的影响是很难预测的.

For example, most predators of waterfowl nests prey opportunistically on songbird nests, and removing(15) these predators could directly increasesongbird nesting success. Alternatively, small mammals such as mice and ground squirrels are important in the diet of many waterfowl-nest(20) predators and can themselves be important predators of songbird nets.

举例,比如迁移一些predators,它们尤其是以songbird nests为食,将可能直接让更多的songbird nest保留下来.

又或者，predators 主要以一些small mammals为食，这些small mammals也吃songbird nests..

Thus. Removing waterfowl-nest predators could affect songbird nesting success through subsequent increases(25) in small-mammal populations.

所以，把这些waterfowl-nest predators迁移走可以通过增加大量的small mammal populations来使songbirds的nest 存活。

觉得矛盾的地方：为什么把那些predators移走了，songbirds存活率就会增加呢？small mammals数量增加不是会导致songbirds nests同样减少吗？困惑ing

第一段结束

In 1995 and 1996, researchers trapped and removed certain waterfowl-nest predators.

９５－９６的时候，移除了一些predators.

primary raccoons and striped skunks, then observed subse(30) quent survival rates for songbird nests.

主要是r和s,观察其后的存活率．

Surprisingly. They observed no significant effect on songbird nestingsuccess.

令人惊讶的是，他们观察到移除这些predator并没对songbird nesting success有影响。

This may be due to several factors. Neither raccoons nor striped(35) skunks consume ground squirrels,which are important predators of songbird nests. Thus, their removal may not have led to significant increases in populations of smallerpredators.

分析原因。第一，是引文r和s都不吃S,S是songbirds nests的重要捕食者。所以，移除他们可能没有导致smaller predators的增加。

(40) Additionally, both raccoons and striped skunks prefer wetlands and spend little time in upland habitats; removing these

species may not have increased the nesting success of songbirds in the uplands enough to allow detection.

其次，r和s都比较喜欢wetlands一般不去upland habitats.所以移除这些生物不会导致 success of songbirds in uplands。。。。

第二个理由也没看懂．．．

第二个理由也没看懂．．．

我就根据我没太看懂的比题目做一下，大家也帮着我看一看，先谢过．．．

我就根据我没太看懂的比题目做一下，大家也帮着我看一看，先谢过．．．

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Q 13:

NOTE: You must scroll to read the answer

choices for this question.

According to the passage, which of the

following is true about the role played

by ground squirrels in the ecology of

grassland-wetland complexes?

A.    While not important in the diet of

raccoons or striped skunks, ground

squirrels are a significant source

of food for other waterfowl-nest

predators.

B.     Whereas ground squirrels are

typically important as predators of

songbird nests, their opportunistic

predation on waterfowl nests also

has an observable effect on water-

fowl nesting success.

C.     Although most waterfowl-nest

predators prey on small mammals

such as mice and ground squirrels,

populations of ground squirrels tend

to increase quickly enough to com-

pensate for this level of predation.

D.    Although ground squirrels have been

known to prey on songbird nests, a

larger portion of their diets is usually

provided by predation on waterfowl

nests.

E.     Since larger predators tend to prefer

small mammals to songbird eggs as

a food source, a large population of

ground squirrels plays an important

role in controlling opportunistic

predation on songbird nests.

完全没思路，不知道选啥．．．

正确答案是Ａ

Answer:

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Q 14:

Which of the following best describes

the function of the sentence “Neither

raccoons…songbird nests” (lines 34-37)

in the context of the passage as a whole?

A.    It raises questions about the validity of a

theory described in the first paragraph.

B.     It points out an oversimplification that is

inherent in the argument presented in

the first paragraph.

C.     It introduces information that may help

explain the results of the experiment

that are presented earlier in the

paragraph.

D.    It provides a specific example of the

type of data collected in the experiment

described earlier in the paragraph.

E.     It anticipates a potential objection to the

conclusions drawn by the researchers

involved in the experiment described

earlier in the paragraph.

Answer:Ｃ

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Q 15:

The primary purpose of the passage is to

A.    describe some procedures used for

wildlife management and consider

some problems associated with the

execution of those procedures

B.     outline a problem related to a wildlife

management procedure and offer

potential explanations for the results of

an experiment bearing on that problem

C.     present experimental results that

illustrate the need for certain wildlife

management procedures and point out

some inconsistencies in those results

D.    argue that a certain procedure used

for wildlife management should be

modified because of its unintended

consequences

E.     propose that further experiments be

performed to assess the long-term

effects of certain wildlife management

procedures

answer:B

Neither raccoons nor striped skunks consume ground squirrels, which are important predators of songbird nests.

ground squirrels are important in the diet of many waterfowl-nest predators and can themselves be important predators of songbird nets.

觉得这里lz是对文章的整体结构的理解上有所偏差，科学家的研究目标是验证songbird nest的存活率是否会降低，而不是是否会增高。整理了一下以供参考：

1.waterfowl-nest predators偶尔会捕猎songbird nests。
2.mice和ground squirrels是waterfowl-nest predator的主要食物
3.mice和ground squirrels是songbird nest的主要捕猎者

从上面可以推断出：移除waterfowl-nest predator将会导致mice和ground squirrels增加，从而导致songbird的nest存活率降低。

于是科学家做了实验来移除一些waterfowl-nest predators，但是发现songbird的存活率并没有受影响。

分析的原因如下：
1. 这些被移除的waterfowl-nest predators向来并不以ground squirrel为食，因此predators的减少并不会导致这些mammal的明显增加。
2. 这些被移除的waterfowl-nest predators对songbird并不太感兴趣，所以移除他们也对songbird nest没什么影响。

关系太复杂了。。。

有没有人能详解下此题，谢谢啦~~~

顶起来~！！

songbird和waterfowl以及其他生物之间的微妙关系

一，两者共同的天敌，除去对两者都有利，w好，s也好

二，small mammal，是w的食物，却吃s（对s不利）。如果移走small mammal的天敌，small mammal多，w好，s不好

实验，将w的天敌挪走，w好，看后果（根据上文，如果是第一种情况的话，应该s好，如果是第二种情况的话，应该s不好。总之是应该有点影响才对）

因此，这里有了一个转折，surprisingly， 对s并没有影响

然后分析，对s没影响（也就是实验结果）的原因进行分析

给了两种可能性

一：针对上文的二，天敌不吃small mammal，天敌走了，对small mammal 没影响，也就对s没影响

二：针对上文的一，w的天敌其实根本就不是s的天敌，那自然对s就没有影响了

仔细看来，两段是有严格对应的

这应该看成是：猜测的一种生物关系——实验结果与猜测不符——解释实验结果

Q13：ground squirrel在一段尾和二段解释部分出现，综合一下就是答案

Alternatively, small mammals such as mice and ground squirrels are important in the diet of many waterfowl-nest(20) predators and can themselves be important predators of songbird nets

Neither raccoons nor striped(35) skunks consume ground squirrels

Q14：划线部分前一句，this  may be due to several factors很明显，后面就应该是factor啦，也就是explain部分了

Q15：文章第一段应该算是一个很重要的背景了，根据此背景，产生了research， 这个research又得出了surprisingly 的结果，然后，作者又给出了解释

agree