（三）

　　You are what you eat. This saying has provided scientists with clues（线索）about the diet of hominids－our early relatives of 3 million years ago.

　　Studying carbon atoms（碳原子）locked up in tooth enamel（珐琅质）， two researchers argue against the widely held belief that hominids ate little more than fruits and leaves. Sponheimer and Julia Lee－Thorp of the University of Cape Town， south Africa， report their findings in Friday‘s Science.

　　There aren‘t many clues for us to know the life of early hominids. The shape of hominids’ teeth offered the first clues. Large and flat-edged with thick enamel， they looked perfect for eating nuts and fruits， different from the sharp teeth one would want to tear into meat with. The first stone tools， which would help in eating meat， didn‘t appear until about half a million years later.

　　Scientists have also found marks on hominids‘ teeth with patterns very similar to those on the teeth of modernday fruit eaters. Sponheimer and Lee-Thorp tried a new method， looking at the chemical composition of the tooth enamel. They studied the enamel for the carbon-13. Animals that eat grasses have higher carbon-13 levels than those eating fruits and other plants.

　　What they found was that the teeth of the hominids had an in-between amount of carbon-13， which meant not only they were eating fruits， they were eating a lot of grass， or animals eating grasses. The lower carbon-13 levels could also come from eating certain types of insects（昆虫）。

　　But there are people who understand differently. Porf. Ungar of the University of Arkansas agrees the study offers new suggestions of hominid diet， but disagrees about the suggestion that meat could explain the lower carbon-13 levels.

　　One suggestion might be true though-take good care of your teeth. In 3 million years， a scientist might be using them to figure out what you ate for dinner.

　　1. Which of the following can be the best title for the text？

　　A. Protect Your Teeth.

　　B. What the Hominid Ate.

　　C. Where the Hominid lived.

　　D. The Formation of Tooth Enamel.

　　2. Before the two scientists‘ findings， most people thought that hominids ______.

　　A. lived half a million years ago

　　B. ate mainly fruits and leaves

　　C. used tools to dig grass

　　D. had sharp teeth

　　3. The two scientists‘ findings were mainly based on the study about ______.

　　A. the shape of hominids‘ teeth

　　B. the teeth marks of early fruit eaters

　　C. the grasses of 3 million years ago

　　D. the make-up of the tooth enamel

　　4. What is it that Prot. Ungar finds doubtful？

　　A. Hominids possibly ate grass-eating animals.

　　B. Hominids probably had different diets.

　　C. Hominids were basically fruit-and grasseaters

　　D. Hominids had lower level of carbon-13 in their teeth.

　　［译文］

　　你的饮食习惯影响着你。这一说法给科学家提供了三百万年前早期人类的饮食线索。

　　通过研究牙齿珐琅质中的碳原子，两位研究人员反驳了被广泛认同的观点：hominids人只吃水果和树叶。南非，开普顿城Thorp大学的Sponheimer和Julia Lee在Friday‘s Science上报道了他们的发现。

　　没有很多的线索供我们了解早期人类的生活。他们牙齿的形状提供了第一线索。大而扁平边缘带有厚的珐琅质的牙齿非常适合他们吃坚果和水果，他们不同于我们撕咬肉用的尖利牙齿。第一批帮助人们吃肉的石器工具，直到大约五十万年前出现。

　　科学家也发现了Hominids人牙齿上的斑痕和现代吃水果人的相似。Sponheimert Julia Lee，尝试了一个新方法，观察了牙齿珐琅质的化学成分，他们研究了珐琅质中的碳原子十三。食草动物中碳原子十三含量高于吃水果和别的植物的动物。

　　他们发现hominids的牙齿的碳原子数量介于这两者之间，那意味着他们不仅吃水果，他们也吃许多草或者食草动物。碳原子数量低可能因为他们吃某些昆虫。

　　但有些人有不同的理解。Arkansas大学的Ungar教授同意研究提供了hominid饮食的新说法，但是他不同意肉能解释碳原子十三水平低这一说法。

　　一种建议是正确的：保护好你的牙齿。三百万年之后，某一科学家可能会使用它们推断出你吃什么食物。

　　[试题答案]

　　（一）答案及分析

　　1. A文章第一段谈到当年龄如此小的孩子要去工作时，你会感到不安，但当听说他们是戏校的学生，他们说的“工作”也就是排戏时，你就放心了。选项A与之符合。

　　2. D作者的观点是一个好的戏校既要学普通文化课又要说戏剧表演。选项D与之一致。

　　3. C此处的professional work指职业性工作，也就是指孩子们的专业，即舞台表演，故选C.选项D中的acting， singing or dancing虽然也是舞台表演，但after class使这些舞台表演成为业余的，而非专业的，与文章不符。

　　4. D文章的最后一段表明作者对孩子的普通文化课教育有所担心，故选D.

　　（二）答案及分析：

　　1. C这是一道细节题。男人只是想买到他所需要的东西，而价格是其次的。“He knows what he wants， and his purpose is to find it and buy it， the price is a less important consideration. ”

　　2. C从文章第二自然段的例子中可看出，男人买夹克衫时在买之前就确定了颜色式样，如果式样不符合他的想法，即使颜色合适，他都不肯花时间试穿一下。

　　3. B这是一道寓意题。从第二段可看出，如果男人买不到自己需要的东西，很少人会有耐心响应售货员的提议去看其他商品。

　　4. A最后一段有这样的句子：“She is always open to persuasion， indeed she considers of great importance what the salewoman tells her， even what her friends tell her. ”这一句说明了女性购物时的心态和特点。

　　5. A这是一道综合推理题。此题要求说出男女购物者最明显的差别。男人如果找到需要的衣服，连试穿带交易不会超过5分钟。而他们对于式样或颜色不适合的衣服连试穿都会委婉地拒绝。女人正相反。她们在试穿衣服时绝不吝啬时间，而丈夫们只好在椅子上坐等。

　　（三）答案及分析：

　　1. B通过研究他们的牙齿推断他们的饮食。

　　2. B第二段“two researchers argue against the widely held belief that hominids ate little more than fruits and leaves”。

　　3. D第四段和第五段论述他们的发现基于牙齿珐琅质的组成。

　　4. A第六段“disagrees about the suggestion that meat could explain the lower Carbon－13 Level”第五段“Animals that eat grasses have higher Cabon-13 levels.”