单选题 Here's a question about chickens and eggs you may not have heard before: How is it that an egg can be so hard to break from the outside, yet so easy for a weak little chick to peck through from the inside?
It's a tough question to crack. Eggshells are thought to change as the chick grows inside. As the creature develops, parts of the inner eggshell dissolve and the fuzzy little bird incorporates some of that calcium into its bones. But it remained unclear how this process influenced eggshell microstructure. Now, As Nicola Davis at The Guardian reports, a new study in Science Advances suggests that it's all about the structure of the egg and how it develops with the growing creature inside.
To solve the mystery and study egg structures, researchers at McGill University used a new method that allowed them to cut extremely thin sections of shell. They then analyzed these thin sections using a microscope to study shell structure.
The team examined the shell of fertilized (受精的)eggs and compared that to unfertilized eggs. As Laurel Hamers at ScienceNews reports, they discovered that the key to the eggs' toughness appeared to be the formation of microstructures, guided into place by proteins. They focused their analysis on one particular protein, which is found throughout the shell and is believed to be vital in the organization of mineral structure.
As Davis explains, the special protein seems to act as a 'scaffold (脚手架)' that guides the structure and density of minerals in the shell, in particular calcium. In a developed egg, the minerals in the outer layer of the shell are densely packed and rich with such special protein. But inner egg layers have a different structure, which has less of such special protein and lower density of mineral packing.
In non-incubated eggs, the nanostructure didn't change. But in the fertilized eggs, the structure of the inner egg appeared to shift over time. Calcium was transferred to the chicks and the inside of the shell grew weaker, making it easier for the chick to crack through. The inner shell also became bumpier (更崎岖不平的), which the researchers believe provides more surface area for chemical reactions that release calcium to the chicks.
Knowing the structure of the egg could lead to new types of materials, says Lara Estroff, a Cornell engineer who was not involved in the study, Hamers reports. The researchers think it could even improve food safety for eggs. About 10 to 20 percent of chicken eggs crack in transport, which could lead to contamination. Understanding why some eggs are stronger than others could help breed chickens with tougher eggs.

单选题 What is the question that the author thinks hard to answer? ______

A、 The question about whether the chicken comes first or the egg comes out first.
B、 Why eggshells are thought to change as the chick grows inside?
C、 Why is it hard to break the eggshell from outside but easy for a chick to get out?
D、 Which egg is harder to break if we boil one in fresh water and the other in salt water?

【正确答案】 C

【答案解析】根据题干中的信息词可以把答题线索定位到第一至二段。文章首段开门见山地提到，这里有一个关于鸡和蛋的问题，你可能以前没有听说过：为什么鸡蛋从外面很难打破，而虚弱的小鸡从里面却很容易啄破?而第二段首句作者紧接着说，这是一个很难回答的问题。由此可知，作者认为难以回答的问题是：为什么鸡蛋从外面很难打破，而小鸡却容易破壳而出?故本题应选C。 [参考译文] 这里有一个关于鸡和蛋的问题，你可能以前没有听说过：为什么鸡蛋从外面很难打破，而虚弱的小鸡从里面却很容易啄破? 这是一个很难回答的问题。人们认为，蛋壳随着小鸡在里面成长而改变。随着这一生物的发育，蛋壳内部的某些部分会溶解掉，而这只毛茸茸的小鸡会把其中的一些钙吸收到骨头里。但这一过程如何影响蛋壳微观结构仍不清楚。现在，据《卫报》的尼古拉·戴维斯报道，《科学进展》杂志的一项新研究表明，这一切都与鸡蛋的结构，以及它是如何随着里面的生物生长而发生变化的有关。为了解开这个谜团，研究鸡蛋的结构，麦吉尔大学的研究人员使用了一种新方法，允许他们切割非常薄的蛋壳。然后他们用一台显微镜分析这些薄切片来研究外壳结构。该团队研究了受精鸡蛋的蛋壳，并将其与未受精的鸡蛋进行了对比。据《科学新闻》的劳雷尔·汉默斯报道，他们发现鸡蛋坚韧度的关键似乎在于微观结构的构成，这是在蛋白质的引导下实现的。他们的分析集中在一种特定的蛋白质上，这种蛋白质在整个蛋壳中都有发现，并且被认为在矿物结构的组织中是至关重要的。戴维斯解释说，这种特殊的蛋白质似乎充当着“脚手架”的角色，指导着蛋壳的结构和矿物质的密度，尤其是钙。在一个发育成熟的鸡蛋中，蛋壳外层的矿物质密集堆积，富含这种特殊的蛋白质。但蛋壳内层结构不同，这种特殊蛋白质的含量较少，矿物质堆积密度较低。在未孵化的鸡蛋中，纳米结构没有改变。但在受精卵中，内卯的结构似乎随着时间的改变而发生了变化。钙被转移到小鸡体内，蛋壳的内部变得越来越易破，使得小鸡更容易破壳而出。内壳层也变得越来越不平整，研究人员认为，这为化学反应提供了更多的表面场所，这种化学反应会释放钙，让小鸡吸收。据汉默斯报道，未参与这项研究的康奈尔大学工程师拉腊·埃斯特洛夫说，了解鸡蛋的结构可能会产生新型材料。研究人员认为它甚至可以改善鸡蛋的食品安全。约10%至20%的鸡蛋会在运输过程中破裂，这可能会导致污染。弄懂为什么有些鸡蛋比其他的鸡蛋更坚固，可以帮助人们饲养蛋壳更坚硬的鸡。

单选题 What did the researchers at McGill University do to study egg structures? ______

A、 They used a microscope to analyze thin sections of eggshells.
B、 They studied the structure of chicks' beak with a microscope.
C、 They compared the shells of raw eggs to those of boiled eggs.
D、 They analyzed the components of white eggs and yellow eggs.

【正确答案】 A

【答案解析】根据题干中的信息词researchers at McGill University，可以把答题线索定位到第三段。第三段提到，为了解开这个谜团，研究鸡蛋的结构，麦吉尔大学的研究人员使用了一种新方法，允许他们切割非常薄的蛋壳。然后他们用显微镜分析这些薄切片来研究外壳结构。由此可知，他们使用了显微镜来分析蛋壳薄切片。故本题应选A。

单选题 What seems to play the most important role in making eggshells tough? ______

A、 The minerals found in the eggshells.
B、 Elements that make up the eggshells.
C、 Metal elements the eggshell contains.
D、 A special protein in the eggshells.

【正确答案】 D

【答案解析】根据题干中的信息词making eggshells tough，可以把答题线索定位到第四段。第四段开头提到，该团队研究了受精鸡蛋的蛋壳，并将其与未受精的鸡蛋进行了对比，而接下来作者指出，据《科学新闻》的劳雷尔·汉默斯报道，他们发现鸡蛋坚韧度的关键似乎在于微观结构的构成，这是在蛋白质的引导下实现的。最后，作者进一步指出，他们的分析集中在一种特定的蛋白质上，这种蛋白质在整个蛋壳中都有发现，并且被认为在矿物结构的组织中是至关重要的。也就是说，这种特殊蛋白质决定了鸡蛋蛋壳的微观结构的构成，而蛋壳的微观结构构成似乎是鸡蛋的坚韧度的关键所在，由此可知，鸡蛋蛋壳中的特殊蛋白质对于蛋壳的坚韧度似乎起着至关重要的作用，故本题应选D。

单选题 What do we know about the inside of eggshells and the outside of eggshells? ______

A、 The inner shell of fertilized eggs is harder to break than that of unfertilized eggs.
B、 The inner shell and the outer shell of an egg are made up of different proteins.
C、 The outer layers of the shell are more densely packed with minerals than the inner egg layers.
D、 It is easier for chemical reactions to occur if the inner shell becomes flatter.

【正确答案】 C

【答案解析】根据题干中的信息词the inside of eggshells和the outside of eggshells，可以把答题线索定位到第五段。第五段提到，在发育成熟的鸡蛋中，蛋壳外层的矿物质密集堆积，富含这种特殊的蛋白质。但蛋壳内层结构不同，这种特殊蛋白质的含量较少，矿物质堆积密度较低。由此可推断，蛋壳外层矿物质密度比内层矿物质密度更大，本题应选C。

单选题 What does the passage say could be a practical application of the new study? ______

A、 Helping a chick crack through the eggshell more easily.
B、 Creating new materials by knowing the structure of eggs.
C、 Making it easier to tell fertilized eggs from unfertilized ones.
D、 Increasing the food safety and improving the taste of egg food.

【正确答案】 B

【答案解析】根据题干中的信息词a practical application of the new study，可以把答题线索定位到最后一段。最后一段指出，据汉默斯报道，未参与这项研究的康奈尔大学工程师拉腊·埃斯特洛夫说，了解鸡蛋的结构可能会产生新型材料，即关于鸡蛋结构的研究可能有助于人们研发出新型材料，故本题应选B。