gwd6-23,25

davidzhn

Conducive 的意思是 有益于，导致， 不是indicative

B说Calcium 和 chrome有益于 Diamand farmation, 显然超出了原文的范围。

流沙

仔仔细细把这段话的前前后后看了一下，同意25选c

25题的题目是“The passage suggests that the presence of G10 garnet in a kimberlite pipe indicates that”，感觉侧重点还是讲pipe。。。

b有点偏题。而且level－》conducive，觉得说不过去。

pactzy

Q23 to Q26:

      Diamonds are almost impos-

       sible to detect directly because they

       are so rare:  very rich kimberlite

Line       pipes, the routes through which

  (5)      diamonds rise, may contain only

three carats of diamonds per ton

of kimberlite.  Kimberlite begins as

magma in Earth’s mantle (the layer

between the crust and the core).  As

(10)      the magma smashes through layers

of rock, it rips out debris, creating

a mix of liquid and solid material.

Some of the solid material it brings

up may come from a so-called

(15)      diamond-stability field, where condi-

tions of pressure and temperature

are conducive to the formation of

diamonds.  If diamonds are to sur-

vive, though, they must shoot toward

(20)      Earth’s surface quickly.  Otherwise,

       they revert to graphite or burn.

       Explorers seeking diamonds look

for specks of “indicator minerals”

peculiar to the mantle but carried up

(25)      in greater quantities than diamonds

and eroded out of kimberlite pipes

into the surrounding land.  The stan-

dard ones are garnets, chromites,

and ilmenites.  One can spend years

(30)      searching for indicators and tracing

them back to the pipes that are their

source; however, 90 percent of

       kimberlite pipes found this way are

barren of diamonds, and the rest

(35)    are usually too sparse to mine.

      In the 1970’s the process of

locating profitable pipes was refined

by focusing on the subtle differ-

ences between the chemical

(40)     signatures of indicator minerals

found in diamond-rich pipes as

opposed to those found in barren

pipes.  For example, G10 garnets,

a type of garnet typically found in

(45)      diamond-rich pipes, are lower in

calcium and higher in chrome than

garnets from barren pipes.  Geo-

chemists John Gurney showed that

garnets with this composition were

(50)      formed only in the diamond-stability

field; more commonly found ver-

sions came from elsewhere in the

mantle.  Gurney also found that

though ilmenites did not form in the

(55)      diamond-stability field, there was a

link useful for prospectors:  when

the iron in ilmenite was highly

oxidized, its source pipe rarely

contained any diamonds.  He rea-

(60)      soned that iron took on more or less

oxygen in response to conditions in

the kimberlitic magma itself—mainly

in response to heat and the avail-

able oxygen.  When iron became

(65)      highly oxidized, so did diamonds;

that is, they vaporized into carbon

dioxide.

Q25:

The passage suggests that the presence of G10 garnet in a kimberlite pipe indicates that

              

1. the pipe in which the garnet is found has a 90% chance of containing diamonds
2. the levels of calcium and chrome in the pipe are conducive to diamond formation
3. the pipe passed through a diamond-stability field and thus may contain diamonds
4. any diamonds the pipe contains would not have come from the diamond-stability field
5. the pipe’s temperature was so high that it oxidized any diamonds the pipe might have contained

我选B. 请看我在文中划出的重点，不知有没有道理，请NN们帮忙看看

我觉得C thus 有点怪怪的。不是因为the piple passed through a diamond-stability field， 才contain diamonds.

携隐

同意C. 看第一段,说明钻石是在field中形成的而不是在pipe中形成的,pipe只是在经过这个field的时候把钻石带出来而已.即使这个pipe中的N多成份适合钻石继续保存,但决不是适合钻石fromation.

这题我本来也选B.看了讨论后对NN们的细心和对阅读的敏感度佩服不已,自己则惭愧不已.看来GWD的阅读已经不再像OG那样遍布小红旗了,开始把纸条藏在石头缝里了.(***,它要玩偶们就陪它玩,who怕who啊)

blur

携隐mm那几个***是什么意思啊。。：）

sunshining

gwd 6-26， 答案是C, 请问B错在什么地方？谢谢

Q26:

According to the passage, Gurney refined the use of ilmenites in prospecting for diamonds in which of the following ways?

1. He found that ilmenites are brought up from the mantle by kimberlite pipes and erode out into the surrounding land in greater quantities than diamonds.
2. He found that since ilmenites do not form in the diamond-stability field, their presence indicates the absence of diamonds.

3. He showed that highly oxidized iron content in ilmenites indicates a low survival rate for diamonds.

4. He found that when the iron in ilmenites is highly oxidized, conditions in the magma were probably conducive to the formation of diamonds.
5. He showed that ilmenites take on more or less oxygen in the kimberlite pipe depending on the concentration of diamonds.

alicely

以下是引用sunshining在2004-10-24 5:33:00的发言：

gwd 6-26， 答案是C, 请问B错在什么地方？谢谢

Q26:

According to the passage, Gurney refined the use of ilmenites in prospecting for diamonds in which of the following ways?

1. He found that ilmenites are brought up from the mantle by kimberlite pipes and erode out into the surrounding land in greater quantities than diamonds.


2. He found that since ilmenites do not form in the diamond-stability field, their presence indicates the absence of diamonds.
   
   
   



3. He showed that highly oxidized iron content in ilmenites indicates a low survival rate for diamonds.
   
   
   



4. He found that when the iron in ilmenites is highly oxidized, conditions in the magma were probably conducive to the formation of diamonds.


5. He showed that ilmenites take on more or less oxygen in the kimberlite pipe depending on the concentration of diamonds.

Gurney also found that  

though ilmenites did not form in the         并没有b 中的因果关系

(55)  diamond-stability field, there was a      

link useful for prospectors:  when

the iron in ilmenite was highly

oxidized, its source pipe rarely

contained any diamonds.  He rea-

(60)      soned that iron took on more or less

oxygen in response to conditions in

the kimberlitic magma itself—mainly

in response to heat and the avail-

able oxygen.  When iron became

(65)      highly oxidized, so did diamonds;

that is, they vaporized into carbon

dioxide.

[此贴子已经被作者于2004-12-24 22:38:47编辑过]

scorpio0001

请问高亮部分如何理解？

Geo-

chemists John Gurney showed that

garnets with this composition were

(50)      formed only in the diamond-stability

field; more commonly found ver-

sions came from elsewhere in the

mantle.  Gurney also found that

skidals

以下是引用scorpio0001在2005-3-11 9:47:00的发言：

请问高亮部分如何理解？

Geo-

chemists John Gurney showed that

garnets with this composition were

(50)      formed only in the diamond-stability

field; more commonly found ver-

sions came from elsewhere in the

mantle.  Gurney also found that

地理化学家JG说明了有这种成份的石榴石(钙含量低，铬含量高)只形成于钻石稳定带(diamond-stability field不知道该怎么翻)；更常见的种类来自于地幔的其他部分。

tqbiao

26的b就是错在没有因果关系，选项c比较符合ets喜欢测试考生对什么高什么就低之类的正确理解！

至于25-c我觉得文章在这里不是 and thus may contain diamonds的问题，我们在这段的开头就知道，这一段谈的是通过化学分析来研究diamnond 是否rich的问题，所以b更加正确，正确就正确在conducive上，因为calcium and chrome in the pipe中就是符合了diamond-rich pipe产生的需求，所以rich的。

请大家指正！