2019新优化一轮高考总复习外研版英语（优课件+优选试题）：选修7 (共18份打包)

Ⅰ.阅读理解 A (2018·广西师大附属外校高三模拟)Every day, people come into contact with thousands of chemicals. These chemicals are said to be harmless to human health. In fact, the chemicals are considered so safe that we wash with them. We put them on our bodies and even our faces. Other chemical products are used throughout our homes. By the time you walk out of your front door, you have already been exposed to thousands of chemicals. On its own, each chemical seems harmless. But in combination with other chemicals, they may become deadly. That is the finding of a two­year study by a high­profile(高调的) task force of scientists. The task force was told to investigate the cancer­causing possibility of chemical mixtures. Linda Gulliver was one of the 174 scientists on the task force. Their job was to study the cancer­causing potential of 85 chemicals. All 85 are said to be common in the environment. Ms Gulliver explains that chemicals have the potential or ability to form dangerous mixtures. Even simple minerals can become dangerous when mixed with chemicals found in plastics or beauty products. Working in groups, the scientists explored how different chemical mixtures could lead to cancer. Ms Gulliver’s team looked at the ability of different combinations to support the increase of malignant(恶性的) human cells. She says the current way to identify whether chemicals cause cancer is to test them one at a time. This method leads, she adds, to a long list of supposedly “safe” chemicals. She and her team say that approach needs to change. “We definitely need certain research…to find out what mixtures of chemicals would be more harmful than others; what groups of chemicals, when together, would produce more harmful effects. And at the moment, that is not known.” An estimated one in five cancers has been linked to chemical exposure. It may turn out that the cancer­causing villain(恶棍) is not a single chemical at all. 语篇导读　本文为科普说明文，揭示了多种安全的化学物质相混或成致癌物。 1．What effect may one single chemical ha