OG13th sc 81求解

diaoshuo518

OG13th sc 81
Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles islands.

A. sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of
B. sloth, that they found in Puerto Rico in 1991, has been dated at 34 million years old, thus making it the earliest mammal known on
C. sloth that was found in Puerto Rico in 1991, was dated at 34 million years old, making this the earliest known mammal of
D. sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on
E. sloth which, found in Puerto Rico in 1991, was dated at 34 million years old, made the sloth the earliest known mammal of
OG答案是选择的D
答案说A中的it指代不明。前面只有a sloth一个单数。fossils是复数。it显然是指代sloth的。怎么会指代不明呢？
D中主语和谓语断开。又和修饰语断开这种形式怎么感觉不太好呢？！并且感觉D这种说法也有歧义啊，并且这里并没有表示明显用完成时代的词。为什么会选择用完成时态呢？
并且D中的making不应该是就近指代么。为什么能跳跃的指代前面的fossils?
求详细的解答。谢谢~

supsophy

iin choice A: fossils made it the earliest mammal... that not make sense
1."of the arm of a sloth" is the modifier of fossils.
2. manhattan 中提到 如果有具体名词和代词同时出现时，同等条件下，具体名词更优

in choice D :      ( , + -ing)      modify the whole clause.
"-ing" can modify the preceding noun, but there doesn't have one.

diaoshuo518

3x。那我可不可以认为重写名词这种方式是一种优选选项呢？还是说看情况具体而论。当然我知道代词风险很大的
还有我想问一下这个现在完成时不是指过去发生的动作对现在的影响么。这题目逻辑含义好像没有这方面的意思？为什么无缘无故用了完成时态呢？

zhudanqing

A，it的指代确实是模糊的，首先lz说肯定不是指代fossils，Y，BUT arm也是单数， sloth也是单数。
     另：A的错误非常明显，逗号+made it the earliest known mammal of 一个完整的句子呢！主语呢？这样悬空可以么？变成两个句子并列且没有连词，硬伤！

D， found in Puerto Rico in 1991你看做插入语好了，去修饰前面的fossils。 V-ING,可以修饰前面一整句话，仅前面的这句话跟后面要有关系！此题的理解是：这个化石追溯到。。。年前，所以这件事表明sloth这个动物是最早的mammal。

个人感觉，不要先从时态着手去排除选项。因为对外国人来说时态很难，如果没有特别的时间标志词的话。
此题，先看句子结构，好几个选项都是有硬伤的

zhudanqing

A，it的指代确实是模糊的，首先lz说肯定不是指代fossils，Y，BUT arm也是单数， sloth也是单数。
     另：A的错误非常明显，逗号+made it the earliest known mammal of 一个完整的句子呢！主语呢？这样悬空可以么？变成两个句子并列且没有连词，硬伤！

D， found in Puerto Rico in 1991你看做插入语好了，去修饰前面的fossils。 V-ING,可以修饰前面一整句话，仅前面的这句话跟后面要有关系！此题的理解是：这个化石追溯到。。。年前，所以这件事表明sloth这个动物是最早的mammal。

个人感觉，不要先从时态着手去排除选项。因为对外国人来说时态很难，如果没有特别的时间标志词的话。
此题，先看句子结构，好几个选项都是有硬伤的

diaoshuo518

我懂了。。十分感谢。。解释的十分清楚~

supsophy

zhudanqing 发表于 2013-10-24 16:15
A，it的指代确实是模糊的，首先lz说肯定不是指代fossils，Y，BUT arm也是单数， sloth也是单数。
     另： ...

不好意思 我有疑义
a 选项并不存在逗号并列两个句子的情况 它的主语是fossils
结构是 fossils +modifiers , made it the earliest known...

supsophy

diaoshuo518 发表于 2013-10-23 23:54
3x。那我可不可以认为重写名词这种方式是一种优选选项呢？还是说看情况具体而论。当然我知道代词风险很大的 ...

1.重写名词通常情况下 是较优的 因为它消除了ambiguity
2.一旦出现 代词 你必须确定：1. 有先行词 必须是个名词
                                      2.先行词与代词的 单复数 必须一致
3.关于代词的ambiguity 和 时态问题
RON 说：it's the last thing we should consider.因为在正确答案中 90% 代词存在ambiguity.

SherlockedJohn

1. it结构上可指代arm也可以指代sloth，但逻辑上应该指代sloth，所以导致歧义。（具体见下）
●pronoun ambiguity：
1. Understand the meaning of the sentence and determine the logical antecedent
Per the sentence:
Certain fossils were found in Puerto Rico in 1991 and are 34M years old.
The presence of these fossils indicates that sloth is the earliest known mammal of GA islands.
Thus, it will only make sense if “it” refers to “sloth”.
2. Determine if there are any other antecedents that can be referred to by this pronoun
Since pronoun “it” is singular, here are the possible antecedents – the singular nouns
• Arm
• Sloth
Notice here that both nouns play similar roles in the sentence – they describe the fossils. Thus, structurally they are at the same level in the sentence. Thus, even though it does not make logical sense for “it” to refer to “arm” since arm cannot be the mammal, structurally it still creates an ambiguity.
3. Select the Correct Answer Choice
Since the pronoun analysis shows an apparent pronoun ambiguity, we will eliminate the answer choice based on other more objective errors:
……
Choice D – Correct – The pronoun ambiguity error has been corrected by replacing the pronoun with the antecedent to eliminate the pronoun usage altogether.
我很支持这里的观点，说不要轻易用咱认为的pronoun ambiguity来作为唯一理由排除选项，因为GMAT里面pronoun ambiguity的标准没那么stringent。这题A选项的逻辑问题很严重。——babybear
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2. A选项，made的主语是fossils，fossils made it the earliest known mammal逻辑语义不对。
D选项，making伴随表结果，体现了正确的逻辑关系：是“dated at ....”造成了“made sloth the earliest known mammal ...”。