[自强不息队]-北京朝阳区2组GMAT复习日记

phoebelulu

天哪，我抢801还有用吗？

昨天总结GWD RC，一个下午只看了16篇，包括做逻辑简图，分类总结都没来得及，哎！速度，时间，矛盾！无论如何，加紧吧，今天打算用中午吃饭的时间做套GWD，然后晚上再做遍OG1O SC，不知道时间够不够，加紧吧！数学也让人头疼，公式基本上忘光光了，从0开始吧，好在10以内的加减法我还会。

加油！

hhdty

顶一下。好久没来了

crowkiller

以下是引用hhdty在2007-9-3 11:44:00的发言：
顶一下。好久没来了

好久不见了，最近准备得怎么样拉...

大家都在等着你的好消息呢.....

crowkiller

貌似Joey今日再度出征..

Bless.................

qianrene

 

To establish such a chronology it is necessary to determine the relative amounts of land ice that existed at various times in the Earth’s past. A recent discovery makes such a determination possible: relative land-ice volume for a given period can be deduced from the ratio of two oxygen isotopes, 16 and 18, found in ocean sediments. Almost all the oxygen in water is oxygen 16, but a few molecules out of every thousand incorporate the heavier isotope 18. When an ice age begins, the continental ice sheets grow, steadily reducing the amount of water evaporated from the ocean that will eventually return to it. Because heavier isotopes tend to be left behind when water evaporates from the ocean surfaces, the remaining ocean water becomes progressively enriched in oxygen 18. The degree of enrichment can be determined by analyzing ocean sediments of the period, because these sediments are composed of calcium carbonate (calcium carbonate: n.[化]碳酸钙) shells of marine organisms, shells that were constructed with oxygen atoms drawn from the surrounding ocean. The higher the ratio of oxygen 18 to oxygen 16 in a sedimentary specimen, the more land ice there was when the sediment was laid down.

 

 

It can be inferred from the passage that precipitation formed from evaporated ocean water has
            

(A) the same isotopic ratio as ocean water

(B) less oxygen 18 than does ocean water

(C) less oxygen 18 than has the ice contained in continental ice sheets

(D) a different isotopic composition than has precipitation formed from water on land

(E) more oxygen 16 than has precipitation formed from fresh water

借人气问个问题啊：）这题选B肯定没问题，但是OG对C的解释是因为the passage suggests that the ocean water evaporates and through subsequent precipitation helps form the ice sheets. So the amount of oxygen18 in ice sheet should be similar to the amount in evaporated water. 难道OG的意思是continental ice sheets是evaporated water转化来的？为什么不是ocean water结冰得来的？

GREVOCA

最近有很多的Admissions Directors的见面会，大家有去吗？不知道有没有帮助。

dennyhuang

以下是引用qianrene在2007-9-3 13:41:00的发言：
 

To establish such a chronology it is necessary to determine the relative amounts of land ice that existed at various times in the Earth’s past. A recent discovery makes such a determination possible: relative land-ice volume for a given period can be deduced from the ratio of two oxygen isotopes, 16 and 18, found in ocean sediments. Almost all the oxygen in water is oxygen 16, but a few molecules out of every thousand incorporate the heavier isotope 18. When an ice age begins, the continental ice sheets grow, steadily reducing the amount of water evaporated from the ocean that will eventually return to it. Because heavier isotopes tend to be left behind when water evaporates from the ocean surfaces, the remaining ocean water becomes progressively enriched in oxygen 18. The degree of enrichment can be determined by analyzing ocean sediments of the period, because these sediments are composed of calcium carbonate (calcium carbonate: n.[化]碳酸钙) shells of marine organisms, shells that were constructed with oxygen atoms drawn from the surrounding ocean. The higher the ratio of oxygen 18 to oxygen 16 in a sedimentary specimen, the more land ice there was when the sediment was laid down.

 

 

 

It can be inferred from the passage that precipitation formed from evaporated ocean water has
   

(A) the same isotopic ratio as ocean water

(B) less oxygen 18 than does ocean water

(C) less oxygen 18 than has the ice contained in continental ice sheets

(D) a different isotopic composition than has precipitation formed from water on land

(E) more oxygen 16 than has precipitation formed from fresh water

借人气问个问题啊：）这题选B肯定没问题，但是OG对C的解释是因为the passage suggests that the ocean water evaporates and through subsequent precipitation helps form the ice sheets. So the amount of oxygen18 in ice sheet should be similar to the amount in evaporated water. 难道OG的意思是continental ice sheets是evaporated water转化来的？为什么不是ocean water结冰得来的？

海洋的水蒸发, 降到陆地,不断蒸发,陆地结冰不断增加,但水分没法再流到海洋

julianfl

以下是引用crowkiller在2007-9-3 13:20:00的发言：

貌似Joey今日再度出征..

Bless.................

Joey加油，貌似最近又开始有不间断性质的FB活动了......

julianfl

以下是引用GREVOCA在2007-9-3 14:21:00的发言：

最近有很多的Admissions Directors的见面会，大家有去吗？不知道有没有帮助。

去的人应该很多吧：）我估计。

qianrene

以下是引用dennyhuang在2007-9-3 14:49:00的发言：

海洋的水蒸发, 降到陆地,不断蒸发,陆地结冰不断增加,但水分没法再流到海洋

这个就是选B的原因啊，但是MM可不可以帮我看一下C啊，谢谢