又来了一题，求教！！！

jameshzd · 发表于 2011-7-14 14:24:32

GWD-12-Q29:

The Earth’s rivers constantly carry dissolved salts into its oceans.Clearly, therefore, by taking the resulting increase in salt levels in the oceans over the past hundred years and then determining how many centuries of such increases it would have taken the oceans to reach current salt levels from a hypothetical initial salt-free state, the maximum age of the Earth’s oceans can be accurately estimated.

Which of the following is an assumption on which the argument depends?

A.The quantities of dissolved salts deposited by rivers in the Earth’s oceans have not been unusually large during the past hundred years.

B.At any given time, all the Earth’s rivers have about the same salt levels.

C.There are salts that leach into the Earth’s oceans directly from the ocean floor.

D.There is no method superior to that based on salt levels for estimating the maximum age of the Earth’s oceans.

E.None of the salts carried into the Earth’s oceans by rivers are used up by biological activity in the oceans.

答案选A，这题目完全没思路啊~牛牛们能给我讲下这题的思路吗？谢谢

jameshzd · 发表于 2011-7-14 14:58:12

有人吗？顶啊！！

灭绝湿太 · 发表于 2011-7-14 16:15:01

GWD-12-Q29:

The Earth’s rivers constantly carry dissolved salts into its oceans.Clearly, therefore, by taking the resulting increase in salt levels in the oceans over the past hundred years and then determining how many centuries of such increases it would have taken the oceans to reach current salt levels from a hypothetical initial salt-free state, the maximum age of the Earth’s oceans can be accurately estimated.
Which of the following is an assumption on which the argument depends?
A.The quantities of dissolved salts deposited by rivers in the Earth’s oceans have not been unusually large during the past hundred years.
B.At any given time, all the Earth’s rivers have about the same salt levels.
C.There are salts that leach into the Earth’s oceans directly from the ocean floor.
D.There is no method superior to that based on salt levels for estimating the maximum age of the Earth’s oceans.
E.None of the salts carried into the Earth’s oceans by rivers are used up by biological activity in the oceans.

答案选A，这题目完全没思路啊~牛牛们能给我讲下这题的思路吗？谢谢
-- by 会员 jameshzd (2011/7/14 14:24:32)

很明显CDE马上可以排除。然后看A取非，就是“准备用来估计大洋年纪的这几百年河水含盐量是异常”，也就是说取样的标本是不准确的。取非后，这个估计方法就是失败的。再看B, salt levels 和 dissolved salts 是两个概念，所以B也不能选。我觉着，如果B的说法改成“At any given time, all the Earth’s rivers carry the same quantities of dissolved salts into oceans ”也是对，和A一个意思。

jameshzd · 发表于 2011-7-14 17:34:33

谢谢你的回答!
A 是正确选项我能理解，就是说sample 没有代表性，sample 不正常，但是B ，salt levels 就是对的啊，原文是说by taking the resulting increase in salt levels in the oceans over the past hundred years，就是看的salt levels的增加量来判断啊。。。B 还是疑惑中。。。

灭绝湿太 · 发表于 2011-7-14 18:16:06

谢谢你的回答!
A 是正确选项我能理解，就是说sample 没有代表性，sample 不正常，但是B ，salt levels 就是对的啊，原文是说by taking the resulting increase in salt levels in the oceans over the past hundred years，就是看的salt levels的增加量来判断啊。。。B 还是疑惑中。。。

-- by 会员 jameshzd (2011/7/14 17:34:33)

rivers constantly carry dissolved salts into its oceans →increase in salt levels in the oceans
河流把溶解盐带入了大洋→ 大洋含盐量的上升。

rivers have about the same salt levels 。河流含盐量相同并不意味着带给大洋的溶解盐相同。极端情况下，某一年地球所有河道全部阻塞，即使所有河流的含盐量没有变化，没有溶解盐流入大洋，大洋的绝对含盐量就没有变化。这种情况下估计方法就会出错。

个人意见，仅供参考......

jameshzd · 发表于 2011-7-15 10:33:36

谢谢你的回答!
A 是正确选项我能理解，就是说sample 没有代表性，sample 不正常，但是B ，salt levels 就是对的啊，原文是说by taking the resulting increase in salt levels in the oceans over the past hundred years，就是看的salt levels的增加量来判断啊。。。B 还是疑惑中。。。

-- by 会员 jameshzd (2011/7/14 17:34:33)

rivers constantly carry dissolved salts into its oceans →increase in salt levels in the oceans
河流把溶解盐带入了大洋→ 大洋含盐量的上升。

rivers have about the same salt levels 。河流含盐量相同并不意味着带给大洋的溶解盐相同。极端情况下，某一年地球所有河道全部阻塞，即使所有河流的含盐量没有变化，没有溶解盐流入大洋，大洋的绝对含盐量就没有变化。这种情况下估计方法就会出错。

个人意见，仅供参考......

-- by 会员灭绝湿太 (2011/7/14 18:16:06)

亲爱滴湿太同学，我自己想明白了，你上面讲的都是你自己强加给argument 的观点。这里不是在追究大海的溶解盐的问题，这题目是说通过测量大海的the increase in salt levels ，并且通过从大海没有salt level 到有salt level 的这个增加量来算花了多少时间形成，去判断大海的最大年龄是多少，也就是大海在多久以前就开始形成了，所以说这和 the Earth’s rivers （就是大海为形成的前身）有没有一样的salt level 或者你说的dissolved salts 都是没有关系的，rivers 不管是否一不一样，判断ocean的最大年龄只和它自身的salt level 花了多少时间形成有关，和rivers 一不一样无关，只是rivers在这里给ocean带来的 salt的增加量。嘿嘿，我觉得我应该是讲明白啦！！！

灭绝湿太 · 发表于 2011-7-15 13:09:43

谢谢你的回答!
A 是正确选项我能理解，就是说sample 没有代表性，sample 不正常，但是B ，salt levels 就是对的啊，原文是说by taking the resulting increase in salt levels in the oceans over the past hundred years，就是看的salt levels的增加量来判断啊。。。B 还是疑惑中。。。

-- by 会员 jameshzd (2011/7/14 17:34:33)

rivers constantly carry dissolved salts into its oceans →increase in salt levels in the oceans
河流把溶解盐带入了大洋→ 大洋含盐量的上升。

rivers have about the same salt levels 。河流含盐量相同并不意味着带给大洋的溶解盐相同。极端情况下，某一年地球所有河道全部阻塞，即使所有河流的含盐量没有变化，没有溶解盐流入大洋，大洋的绝对含盐量就没有变化。这种情况下估计方法就会出错。

个人意见，仅供参考......

-- by 会员灭绝湿太 (2011/7/14 18:16:06)

亲爱滴湿太同学，我自己想明白了，你上面讲的都是你自己强加给argument 的观点。这里不是在追究大海的溶解盐的问题，这题目是说通过测量大海的the increase in salt levels ，并且通过从大海没有salt level 到有salt level 的这个增加量来算花了多少时间形成，去判断大海的最大年龄是多少，也就是大海在多久以前就开始形成了，所以说这和 the Earth’s rivers （就是大海为形成的前身）有没有一样的salt level 或者你说的dissolved salts 都是没有关系的，rivers 不管是否一不一样，判断ocean的最大年龄只和它自身的salt level 花了多少时间形成有关，和rivers 一不一样无关，只是rivers在这里给ocean带来的 salt的增加量。嘿嘿，我觉得我应该是讲明白啦！！！

-- by 会员 jameshzd (2011/7/15 10:33:36)

明白了！~ 我之前的思路很不对昂！~~~多谢你的解答！！！！！！！

又来了一题，求教！！！

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又来了一题，求教 ！！！

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又来了一题，求教！！！