LSAT－4－1－19

swimmingfrog

19.   A tree’s age can be determined by counting the annual growth rings in its trunk. Each ring represents one year, and the ring’s thickness reveals the relative amount of rainfall that year. Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk. Each tomb was constructed from freshly cut logs, and the tombs builders were constrained by tradition to use only logs from trees growing in the sacred laceName w:st="on">PazyryklaceName> laceType w:st="on">ValleylaceType>.

Which one of the following, if true, contributes most to an explanation of the archaeologists’ success in using annual rings to establish the relative ages of the tombs at the Pazyryk site?

(A) The Pazyryk tombs were all robbed during ancient times, but breakage of the tombs seals allowed the seepage of water, which soon froze permanently, thereby preserving the tombs’ remaining artifacts.

(B) The laceName w:st="on">PazyryklaceName> laceType w:st="on">ValleylaceType>, surrounded by extremely high mountains, has a distinctive yearly pattern of rainfall, and so trees growing in the laceName w:st="on">PazyryklaceName> Valley have annual rings that are quite distinct from trees growing in nearby valleys.

(C) Each log in the Pazyryk tombs has among its rings a distinctive sequence of twelve annual rings representing six drought years followed by three rainy years and three more drought years.

(D) The archaeologists determined that the youngest tree used in any of the tombs was 90 years old and that the oldest tree was 450 years old.（C）

(E) All of the Pazyryk tombs contained cultural artifacts that can be dated to roughly 2300 years ago.

I searched those old posters,but none of them solve my puzzle.why not choose B?

B 错在哪里?

new_new

本题是要通过长在Pazyryk laceType w:st="on">Valley里树的年轮来估计the relative ages of the tombs at the Pazyryk sitelaceType>

laceType w:st="on">B的答案只不过说长在Pazyryk laceType w:st="on">Valley里的树的年轮和长在附近其他峡谷里的树的年轮不同。根据这个信息我们还是无法测算出墓的年代啊。而答案C则给出了我们测算年代的信息。laceType>laceType>

swimmingfrog

本来以为只要是distinctive yearly pattern 就可以determine the relative ages of ancient tombs 。忽略了还要有精确的数字才行的。

dalunzi

swimmingfrog，在妞妞解释基础上补充一下，这题的重点在于根据年轮精准的确定年代。B侧重说明Pazyryk laceType w:st="on">Valley里的树的年轮有独特性，意在进一步肯定 “use only logs from trees growing in the sacred laceName w:st="on">PazyryklaceName> laceType w:st="on">Valley”，我们最多只能通过这一特点确定墓里的木材是否都来自Pazyryk laceType w:st="on">Valley。即便都来自Pazyryk laceType w:st="on">Valley，laceType>但此时不排除出现这样的的情况：这些来自Pazyryk laceType w:st="on">Valley的树木所体现的年轮特征却不相同。这样科学家即便知道这些木材确实来自Pazyryk laceType w:st="on">Valley，却无发根据年轮准确判断年代。laceType>而C侧重表明墓中所有木材年轮具有相同特征，最大限度保证了准确，五个答案中C最好。

hedonism555

这是一道经典的LSAT难题， 除了逻辑分析能力之外， 没点想象力还真搞不定它。 称它为“牛人杀手”或“牛见愁”应该不为过了。

三脚猫

我还是不明白哎。B中由于每年的雨量有区别，因此年轮长的也应不一样，我觉得可以从雨量和年轮的相关性来确定tomb的年份。而C只能算出tomb是用生长了多少年的木材建造的。

是不是我把题目的意思理解错了，请dalunzi指教

suibian

每年的雨量跟年轮的厚度有关（the ring’s thickness reveals the relative amount of rainfall that year）注意文章没有说每年的雨量有区别。

B：The laceName w:st="on">PazyryklaceName> laceType w:st="on">ValleylaceType>, surrounded by extremely high mountains, has a distinctive yearly pattern of rainfall, and so trees growing in the laceName w:st="on">PazyryklaceName> laceType w:st="on">ValleylaceType> have annual rings that are quite distinct from trees growing in nearby valleys.

Pazyryk Valley 树木的年轮是跟邻近的山谷里的树木的年轮有区别。a distinctive yearly pattern of rainfall, 有可能每年都是一样的降雨量，只不过跟邻近的山谷里的树木不一样（因为surrounded by extremely high mountains）那么树的年轮就是一样的，这样的话，怎么根据年轮判断tomb的年代呢，只能知道tomb是用生长了多少年的木材建造。

但如果知道了树木的年轮是连续12个6年干旱，3年雨年，3年干旱（six drought years followed by three rainy years and three more drought years.）这样一个年轮模式的话，根据历史记载，应该知道tomb 的那一年是第几个旱年或雨年，也就知道了是哪个年代造的tomb 了。

只是个人意见，还需nn 指点

laceType w:st="on">laceType>

[此贴子已经被作者于2005-1-7 10:34:35编辑过]

lawyer_1

本题最关键明白两点

1。考古学家要确定的是相对年龄，不是绝对年龄

2。明确C的意思：坟墓中的每根LOG都有一个独特的相同的年轮组合（A  DISTINCTIVE）

  即每根LOG都经历过相同的年代，而每根LOG从这个相同时代到被砍下的时间距离可知，那末不同坟墓的相对年龄也就可知拉

[此贴子已经被作者于2005-1-7 20:25:54编辑过]

三脚猫

多谢suibian 和 lawyer,  我明白了

hedonism555

The key here is reading comprehension.

Archaeologists successfully used annual rings to determine the relative ages of ancient tombs at Pazyryk.

These words ==> comparable oldness between tombs at P.

Be careful, it is not to judge the overall age of tombs nor that of any single tomb there.

就是让你比较那些坟比较早， 那些比较晚。 并不是一定找出确定的坟龄。

所以， C is ok in that the distinctive patern can show you which tomb is older.

也就是说， 无论那些树是一百年还是二百年， 其中有十二年的年轮遵循一个模式。 所以， 无论这些树是哪一年砍的， 这要对应上这个模式， 就可知那棵树是较晚时砍的， 也就是哪个坟更晚。

其实， 也用不着考虑这十二年的年轮是怎么安排的。 就把它当成一个标记就可以了。

sort of like these

1 1 1 2 1 1 1  ( one ring)

      1 2 1 1 1 1  (another )

Above 2 represents the distinctive sequence.