综合写作24

  Reading

  Animal fossils usually provide very little opportunity to study the actual animal tissues, because in fossils the animals' living tissues have been largely replaced by minerals. Thus, scientists were very excited recently when it appeared that a 70-million-year-old fossil of Tyrannosaurus rex (T. rex), a dinosaur, might still contain remains of the actual tissues of the animal. The discovery was made when researchers deliberately broke open the T. rex’s leg bone, thereby exposing its insides to reveal materials that seem to be remains of blood vessels, red blood cells, and collagen matrix.

  First, the breaking of the fossilized leg bone revealed many small branching channels inside, which probably correspond to hollows in the bones where blood vessels were once located. The exciting finding was the presence of a soft, flexible organic substance inside the channels. This soft substance may very well represent the remains of the actual blood vessels of T. rex.

  Second, microscopic examination of the various parts of the inner bone revealed the presence of spheres that could be the remains of red blood cells. Tests showed that the spheres contained iron-a material vital to the role of red blood cells in transporting oxygen to tissues. Moreover, the spheres had dark red centers (substances with iron tend to be reddish in color) and were also about the size of red blood cells.

  Third, scientists performed a test on the dinosaur leg bone that showed that it contained collagen. Collagen is a fibrous protein that is a main component of living bone tissue, in which it forms a so-called collagen matrix. Collagen (or its chemical derivatives) is exactly the kind of biochemical material that one would expect to find in association with bone tissue.

  Listening

  As much as we would like to have the remains of actual dinosaur tissue, there are sound reasons for being skeptical of the identifications made in the reading.

  First, the soft, flexible substance inside the bone channels isn’t necessarily the remains of blood vessels. It is much more likely to be something else. Like what? You might say. Well, long after an organism is died, bacteria sometimes colonize hollows, empty areas in bones, like the channels that once held blood vessels. When bacteria lived inside bones, they often leave behind traces of organic material. What the researchers in the reading are identifying as blood vessels might just be traces of soft and moist residue left by bacteria colonies.

  All right. What about the iron-filled spheres? Well, the problem is that scientists found identical reddish spheres in fossils of other animals found in the same place. That includes fossils of primitive animals that did not have any red blood cells when they were alive. Clearly, if these spheres appear in organisms that did not have any red blood cells, then the spheres cannot be the remains of red blood cells. The spheres probably have a very different origin. They are probably just pieces of reddish mineral.

  Third, the collagen. The problem is that we have never found collagen in animal remains that are older than one hundred thousand years. Collagen probably cannot last longer than that. Finding collagen from an animal that lived seventy million years ago would really contradict our ideas about how long collagen can last. It is just too improbable. The most likely explanation for the presence of collagen is that it doesn’t come from the T.rex, but from another much more recent source. For example, human skin contains collagen, so the collagen may have come from the skin of the researchers who are handling the bone.

  一、阅读听力要点概括

  Reading Passage

  Main points: A recently found T.rex fossil might contain actual tissues of the dinosaur.

  Sub point 1: Small channels with organic substance inside leg bone could be blood vessels.

  Sub point 2: Presence of iron spheres could indicate red blood cells.

  Sub point 3: Collagen matrix being showed after a test.

  Lecture

  Attitude: Skeptical.

  Sub Point 1: Bone channels could be caused by something else like bacteria. (Bacteria leave remains)

  Sub Point 2: Iron filled spheres may not indicate any red blood cells. (On no blood cell animal, could be mineral.)

  Sub Point 3: Collagen cannot last longer than 100,000 years. (Could be skin)

  Answer

  二、范文逐段赏析

  Paragraph 1

  The lecturer extends possible explanations beyond the conclusions made on the newly discovered T. Rex fossil and suggests that the existing evidence can point to something other than just the remaining animal tissues, as suggested in the reading passage.

  此段功能:

  (Listening passage后文提到用L代替)

  (Reading passage后文用R代替)

  以L的观点出发,指出L和R的逻辑关系为against。R觉得新发现的恐龙化石上的一些现象表明了化石可能保存了恐龙本身的生物组织。L觉得R中列举的证据不足以支持R的观点,遂用这些证据举出新的观点,做出更合理的解释。紧接着可以展开讨论。

  此段结构:

  作者用一句话表明了逻辑关系和观点。注意L只是怀疑R的发现并做出新解释,不是从发现到结论都反对R。逻辑关系就是L怀疑R的观点并做出新的解释,同时在句中具体复述了R的观点是恐龙骨上有生物组织。

  Paragraph 2

  First, the branching channels in that leg bone may be traces of colonies of bacteria, since bacteria always take the hollows in a bone structure and grow themselves following the existing contours of organic material. And the soft substance inside the channels could be the residues of these bacteria colonies, rather than desiccated blood vessels, as suggested by the reading material.

  此段功能:

  对第一个现象L和R的争论。先复述L的观点,骨头中的细小通道里的生物体可能是由于细菌死亡的原因。随即说明,这些个生物体不是R中说的由于血管留下的。

  此段结构:

  此段为分分结构。作者先写L对发现残留生物体的解释,从发现到解释之间的想法,然后再说明同样的发现R是怎么解释的。

  Paragraph 3

  Second, the reading assumes the reddish spheres found in the bone are red blood cells, citing their color and size. But other fossils of primitive organisms in the same general area also contain similar reddish spheres. With the knowledge that such primitive organisms could not yet have evolved red blood cells, there is good reason to believe that these spots are only reddish mineral deposits, and not blood cells. The reading again makes an imprudent conclusion here.

  此段功能:

  对第二个现象,发现红色球状体,L和R分别进行了解释。R觉得这些红色球的形状和大小意味着他们可能是骨头里的血红细胞。L觉得这样不对,因为在一些原始生物体(Primitive organism)的化石上,也有这样大小颜色的红色球,但这些原始生物根本没有血红细胞。所以对于红色球更合理的解释是,他们是红色矿物质的沉积。L还说R的这种解释太不谨慎了。

  此段结构:

  此段为总分结构,作者在第一句中用R的结论做总,然后接下来的L的两句话,先补充现象再补充结论,推翻了R的结论。

  Paragraph 4

  Third, not a single sample of collagen found to this date is older than 100 thousand years in age. The collagen found at the site spoken of in the passage, however, is located in a seventy million year-old dinosaur fossil. Since this tissue can hardly sustain such a long history, its source may not be a prehistoric animal, but rather the skin of researchers. Hence, the final conclusion of the reading is cast in doubt.

  此段功能:

  在第三个现象的争论上,同样是发现了骨胶原组织。L说现在证据表明存在任何大于100,000年骨胶原组织,更何况一个70,000,000年的恐龙化石。对于骨胶原组织出现的合理解释,不是R所说的史前动物留下的,更有可能是近代学者留下的,比如皮肤。所以R的结论十分值得怀疑。

  此段结构:

  此段为了达到最后证明R的结论不靠谱,L先列举了组织可能是骨胶原的条件,然后说发现的组织完全不符合这个条件,所以只能尝试用新的观点去解释他。最后达到怀疑R结论的目的。

  三、范文全篇总评

  1、 逻辑结构

  全文遵从总分结构,开头段表明L的主要逻辑是怀疑和立出新解释,这篇文章里L并不是一个全盘否定的态度,更多的是遵从证据尝试做出更完整更合理的解释。

  随后三段依照3个分论点依次展开。

  一个观点的确立有3步骤:发现证据或现象,合理解释现象(解释最好带有普遍性),最后确立观点。为了推翻一个观点,对第一步,第二步都可以进行攻击。

  在第一,第二分论点中,作者说明L没有怀疑R发现的证据,只是作出了不同解释。在第三论点中,L对R发现的证据都觉得不合理,自然不同意R的结论。

  2、语言表达

  文中并没有涉及太多有难度的连接词,单词难度主要来自专业名词。可以借鉴的句式有:

  1. The lecturer extends possible explanations beyond the conclusions(旧的结论) made on the newly discovered (新的现象和证据)and suggests that the (新的结论)

  同学们觉得L和R没有强烈的对抗情绪,而L是打算对R做出进一步解释可以用这样的句式。

  2. Imprudent: 不谨慎的,不明智的

  /Careless/ Unthoughtful/

  3. It is imprudent of you to lend money to a stranger.

  4. Cast in doubt: 有疑问的

  /Suspectful / Undetermined/

  The old theory has cast in doubt by some newly found evidence.

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