求问一道逻辑题700-800，是题出错了吗？

1998JIN

Zoologists warn of an imminent surge in the number of bird species that will become extinct within this century. Nevertheless, these zoologists are wrong. One need only consider the information gathered on native North American raptors, such as bald eagles and peregrine falcons. Several of these species came close to vanishing between 1900 and 1970, but since 1970, the local populations of these raptors have rebounded. The answer to which of the following questions provides information that would be most helpful in evaluating the argument above?
• How many species of non-native raptors have been introduced into North America since 1970?
• What special efforts, if any, have been made to rescue native North American raptors since 1970?
• How many years’ experience do the zoologists have in evaluating patterns of extinction among animals?
• To what degree have native North American raptors migrated to other parts of the world?
• How many acres of woodland are set aside each year as bird refuges?








粗体是我理解的结论，也是我认为应该去加强or削弱的东西
B 我大概懂了，但是A 为什么不对啊？如果non native很多，那怎么能那native的去代表整体呢？

joeyqiushi

论点是是否会有大量的鸟在本世纪灭绝。
作者认为不会。
①这里结论说的是大量的鸟在本世纪灭绝，和是不是美国native的没有关系。不管是不是native，对于灭绝来说没有区别。
②从常识来讲，作者用native raptors来举反例，并不需要代表整体。

1998JIN

joeyqiushi 发表于 2019-9-27 19:02
论点是是否会有大量的鸟在本世纪灭绝。
作者认为不会。
①这里结论说的是大量的鸟在本世纪灭绝，和是不是美 ...

但是之所以选B 不就是因为B 指出这个反例不能代表整体吗？

joeyqiushi

看这句话"Several of these species came close to vanishing between 1900 and 1970, but since 1970, the local populations of these raptors have rebounded"。作者用这个例子证明 鸟类具有 population rebound 的能力 --> 不会出现大量灭绝 。其中的 assumption 是这些 raptors 的 populations rebounded 是自然现象。如果说 rebounded 的原因是一些救护措施，那么这个例子就不能证明鸟类具有 rebound 的能力，也就不能证明不会出现大量灭绝了。

1998JIN

joeyqiushi 发表于 2019-9-28 20:00
看这句话"Several of these species came close to vanishing between 1900 and 1970, but since 1970, the ...

谢谢！我好像明白了~

1998JIN

joeyqiushi 发表于 2019-9-28 20:00
看这句话"Several of these species came close to vanishing between 1900 and 1970, but since 1970, the ...

The average age of chief executive officers (CEO’s) in a large sample of companies is 57. The average age of CEO’s in those same companies 20 years ago was approximately eight years younger. On the basis of those data, it can be concluded that CEO’s in general tend to be older now.

Which of the following casts the most doubt on the conclusion drawn above?

(A) The dates when the CEO’s assumed their current positions have not been specified.

(B) No information is given concerning the average number of years that CEO’s remain in office.

(C)The information is based only on companies that have been operating for at least 20 years.

(D) Only approximate information is given concerning the average age of the CEO’s 20 years ago.

(E) Information concerning the exact number of companies in the sample has not been given.

我好像还是不明白

这个题目不也是说举例不充分吗？那non-native如果存在，不也说明他只拿native举例不充分吗？。。

joeyqiushi

A的问题可多了。楼主既然有疑问，那我们挨个分析一下：
①全集是bird species。native North American raptors的补集不是non-native raptors。其它鸟类呢？A不能解决样本偏差问题。
②即便A说的是bird species other than native North American raptors，也有问题。A选项说的是有多少 have been introduced 了？have been introduced 属于不相关的行为。我们要找的是，有多少其它bird species有或者没有rebound的行为。A不仅没有找对其它bird species，还说的是另外的行为，totally irrelevant。
③GMAT的逻辑都是common sense，即这些case在现实生活的场景中就是这样的。人物X说所有鸟类都能飞，人物Y反驳说鸡就没法飞。Y的反驳有样本不足的问题吗？没有。所有鸟类都能飞 的反驳是 不是所有鸟类都能飞。并不是所有鸟类都不能飞。A选项在这个例子中类似于评估 有多少鸭子会游泳（随便瞎想的行为哈，总之不是飞）？

1998JIN

joeyqiushi 发表于 2019-9-29 19:07
A的问题可多了。楼主既然有疑问，那我们挨个分析一下：
①全集是bird species。native North American rapt ...

太感谢了，现在我终于明白啦~！

AMBER513

看一下！