Every time you drive, fly on a plane, or water your lawn, you depend on reinforced rubber. It is used in car and aircraft tires, seals, and countless everyday items. For nearly a century, scientists have known that adding tiny particles called carbon black makes soft rubber much stronger and more durable. This is why tires are black and can withstand years of heat and stress. Yet exactly how this strengthening works remained a mystery.

Now, a team led by engineering professor David Simmons has solved this mystery. Using nearly 1,500 molecular (分子的) dynamics computer simulations, they discovered a key mechanism: a property called Poisson’s ratio mismatch causes rubber to resist changes in its volume when stretched. “We’ve been using this for almost a hundred years without really knowing how it works,” Simmons said. Tire companies have had to rely on trial and error to select the right carbon black.

When a normal rubber band is stretched, it becomes thinner while its volume stays almost the same. But when carbon black particles are added, they act like tiny supports, limiting how much the rubber can thin. As a result, the rubber is forced to expand in volume, which it naturally resists. The material “fights against itself,” leading to a huge increase in strength. The new findings unite earlier theories. The team showed that particle networks, sticky effects, and simple space-filling all contribute to resisting volume change—they are different aspects of a single process.

1.1. What has puzzled scientists about reinforced rubber for nearly a hundred years?

A Why rubber turns black.

B How carbon black works.

C Where rubber is produced.

D When rubber became popular.

解析：选B。B 细节理解题。根据第一段“Yet exactly how this strengthening works remained a mystery.”可知，近百年来科学家早已知道添加炭黑能增强橡胶性能，但一直困惑于炭黑究竟是如何起到强化作用的。A选项“橡胶为什么变黑”只是表面现象，并非科学家困惑的问题；C选项“橡胶产地”、D选项“橡胶何时流行”原文均无提及。故选B。

2.2. The underlined word “mechanism” in Paragraph 2 is closest in meaning to ________.

A a chemical formula

B a working principle

C a physical structure

D a testing method

解析：选B。B 词义猜测题。根据第二段“they discovered a key mechanism: a property called Poisson’s ratio mismatch causes rubber to resist changes in its volume when stretched.”可知，后文冒号后是对该词的具体解释，说明炭黑强化橡胶的内在作用方式与原理，对应a working principle（工作原理）。A选项“化学式”、C选项“物理结构”、D选项“测试方法”均不符合语境。故选B。

3.3. According to the new findings, what truly caused past disagreements among scientists?

A They explained the same process differently.

B They observed the particles incorrectly.

C They lacked modern computer tools.

D They focused on the wrong material.

解析：选A。A 推理判断题。根据第三段“The new findings unite earlier theories. The team showed that particle networks, sticky effects, and simple space-filling all contribute to resisting volume change — they are different aspects of a single process.”可知，以往多种理论其实是同一过程的不同角度，由此推断科学家过去产生分歧，是因为对同一个过程做出了不同解读。B选项“错误观察粒子”、D选项“关注错误材料”原文无依据；C选项“缺少电脑工具”只是研究条件，不是观点分歧的原因。故选A。

4.4. What is the last paragraph mainly about?

A The cause of a space tragedy.

B The trouble with the Magic Triangle.

C The practical value of the new findings.

D The history of rubber reinforcement.

解析：选C。C 主旨大意题。根据最后一段“The findings could transform tire manufacturing…Beyond tires, the gain in knowledge opens the door to designing safer, more durable materials for critical systems like power plants and spacecraft.”可知，本段主要介绍新研究成果在轮胎制造、电站、航天等领域的应用价值和现实意义。A选项“航天悲剧原因”、B选项“魔幻三角困境”只是局部细节；D选项“橡胶强化历史”本段并未涉及。故选C。