As people grow older, an enzyme known as PEP increasingly breaks down the neuropeptide chemicals involved in learning and memory. But now, researchers have found compounds that prevent PEP from breaking neuropeptides apart. In tests, these compounds almost completely restored lost memory in rats. The use of these compounds should be extended to students who have poor memory and difficulty in concentrating-and therefore serious problems in school performance. Science finally has a solution for problems neither parents nor teachers could solve.

In this argument, the arguer states that researchers have found compounds that keep an enzyme known as PEP from breaking neuropeptides apart, which are known to be involved in learning and memory. The arguer states that tests have shown that these compounds almost completely restored lost memory in rats, and that therefore, these compounds should be administered to students with poor memory and difficulty in concentrating. This argument is unconvincing because it contains several critical flaws in logic.

First of all, the arguer states that as people grow older, PEP breaks down the neuropeptide chemicals that are involved in learning and memory. It is true that generally, as people get older, they tend to have more problems with learning and memory. However, there is no direct link mentioned between the breaking down of the neuropeptide chemicals and the loss of learning ability or memory. Additionally, the arguer mentions neuropeptide chemicals that are broken down by PEP. What the researchers have found is a compound that prevents neuropeptides from breaking apart. These are two different physical actions: the breaking down of neuropeptide chemicals as opposed to the breaking apart of the neuropeptides themselves. Furthermore, it is not stated which of these physical actions is involved with the loss of learning ability and memory. It is not explicitly stated that the breaking down of chemicals causes a loss in learning ability and memory, only that this happens as people grow older. It is also not expressly stated whether the breaking apart of the neuropeptides themselves causes memory loss or a lessened learning ability. Without showing a direct link between the effect of keeping the neuropeptides from breaking apart and a reduction in the loss of memory and learning ability, the efficacy of the compounds is called into question.

Secondly and most obviously, the compounds were only tested on rats. Rats may have a similar genetic structure to humans, but they are most certainly not the same as humans. There may be different causes for the learning and memory problems in rats as opposed to that of humans. The effect of the compounds on rats may also be very different from their effect on human beings. It is absurd in the extreme to advocate giving these compounds to students, even assuming that they would help the students with their studies, without conducting further studies assessing the compounds' overall effects on humans. The argument fails on this particular fact if for no other reason.

Additionally, the arguer begins his or her argument by stating that "as people grow older", PEP breaks down the neuropeptide chemicals involved in learning and memory. At the end of the argument, the arguer advocates extending the compounds that prevent PEP from breaking neuropeptides apart to students who have poor memory and difficulty in concentrating. Students are generally young, not older people. There is no evidence presented that shows what actually causes students to have a poor memory or difficulty in concentrating. Indeed, it is more likely that it is extracurricular activities or a lack of sleep that causes such problems in students, not a problem associated with aging. It is highly unlikely that even if the stated compounds could help prevent the memory loss and decreased learning ability associated with aging that it would have any benefits for students.

In summary, the arguer fails to convince with the argument as presented. To strengthen the argument, the arguer must show a direct link between the breaking apart of neuropeptides and loss of memory and learning ability. Additionally, he or she must show that students' poor memory and difficulty in concentrating is a result of the same process, and that the researcher's compounds would have as beneficial an effect on humans as it seems to have on rats.

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［题目］

随着人们日渐衰老，一种被称为PEP的酶会不断地分解学习与记忆过程中所涉及到的神经肽化学物。但现在，研究人员已发现了可阻止PEP致使神经肽分裂的化合物。在测试中，这些化合物几乎在老鼠身上能完全恢复缺失的记忆。这些化合物的运用应该也推广到记忆力衰弱或专注力有困难的学生身上，不然将会造成学业表现上的严重问题。科学终于解决了那些令家长和老师束手无策的问题。

[范文正文]

在本段论述中，论述者指出，研究人员已发现了某些化合物，可以阻止一种被称为PEP的酶的物质将神经肽予以分解，而神经肽则是学习和记忆过程中所需涉及到的物质。论述者还宣称，检测结果表明，这些化合物几乎完全恢复了老鼠身上缺失的记忆。因此这些化合物应该让那些记忆力差和难于集中注意力的学生服用。这段论述缺乏说服力，因为它包含着某些逻辑推理方面甚为严重的缺陷。

首先，论述者称，随着人们渐趋衰老，PEP 会分解学习和记忆过程中所涉及的神经肽化学物。确实，随人们渐趋衰老，他们往往会在学习和记忆方面遭遇诸多问题。但是，在神经肽化学物的分解以及学习能力与记忆力丧失之间，却没有提到任何直接的联系。除此之外，论述者提及被PEP所分解的几种神经肽化学物。但研究人员所发现的只是一种可阻止神经肽不致于分裂的化合物。这是两种不同性质的物理作用：神经肽化学物的分解有别于神经肽自身的分裂。此外，原论述并未陈述这两种物理作用中的那一种与学习能力和记忆能力的丧失相涉。论述者没有明确陈述化学物的分解导致了学习能力和记忆能力的丧失，而只是陈述这种情形只是随着人们日趋年迈而发生。原论述中也没有确切地陈述神经肽自身的分裂是否会导致记忆缺失或学习能力下降。如果无法在阻止神经肽分裂所能产生的作用与减少记忆能力和学习能力丧失之间证明某种直接的联系，那么，化合物的效用将令人质疑。 第二，也是极为明显地，化合物只是在老鼠身上进行了测试。虽然老鼠与人类具有类似的基因结构，但它们无论如何并不等同于人类。对于学习和记忆问题，老鼠所遇到的原因很可能全然不同于人类所遇到的原因。在没有作进一步的研究来估评化合物对人类所产生的总体效果的情况下，就去提倡将这些化合物供学生服用，甚至假设它们有助于学生提高其学习效果，这实乃荒唐至极。即使不是出于其他原因的话，就这一特定事实本身，该段论述根本就站不住脚。 进一步而言，论述者在其论述的开始陈述道，"随着人们渐趋衰老"，PEP会将学习和记忆过程中所涉及的神经肽化学物进行分解。在论述的结尾之处，论述者倡导将那些可阻止PEP致使神经肽分裂的化合物推广至那些记忆力和专注力差的学生身上。学生普遍而言都是年轻人，而不是老年人。论述者没有拿出任何证据来证明究竟是什么原因实际导至学生们记忆力和专注力下降。较有可能的是，是那些课外活动，或缺少充足的睡眠，导致了学生身上的这些问题。即使所提及的那些化合物真的有助于防止与衰老相关的记忆缺失问题和学习能力下降问题，它们也极不可能也能为学生带来任何的裨益。 总而言之，论述者没能用其提出的论据来说服我们。若要使其论述在逻辑上成立，论述者必须在神经肽的分裂与记忆能力和学习能力的缺失之间证明某种直接的联系。此外，论述者必须证明学生记忆能力差和注意力难以集中均是同一过程造成的，并且研究人员所发现的化合物对人类所产生的效果会对老鼠似乎所产生的效果同样的好。