专题06 七选五10篇-2022-2023学年高一下学期英语期末复习考前专练（外研版2019）

专题06 七选五10篇 1 What Is Particulate Matter? There are things floating around in the air. Most of them, you cannot even see. They are a kind of air pollution called particles or particulate matter. In fact, particulate matter may be the air pollutant that most commonly affects people’s health. Have a Look. Particles can come in almost any shape or size, and can be solid particles or liquid droplets. 1 These groups differ in many ways. One of the differences is size. We call the bigger particles PM 10 and we call the smaller particles PM 2.5. BIG. The big particles are between 2.5 and 10 micrometers (from about 25 to 100 times thinner than a human hair). These particles are called PM 10 (we say “PM ten”, which stands for Particulate Matter up to 10 micrometers in size). 2 SMALL. The small particles are smaller than 2.5 micrometers (100 times thinner than a human hair). 3 We say “PM two point five”, as in Particulate Matter up to 2.5 micrometers in size. The smaller particles are lighter and they stay in the air longer and travel farther. PM 10 (big) particles can stay in the air for minutes or hours while PM 2.5 (small) particles can stay in the air for days or weeks. And travel? 4 PM 2.5 particles go even farther— many hundreds of miles. Particulate Matter and Your Health. Both PM 10 (big) and PM 2.5 (small) particles can cause health problems, specifically respiratory (呼吸的) health. When you breathe, you take in the air along with any particles that are in the air, like heavy metals and cancer-causing organic compounds. 5 Exposure to particulate matter leads to increased use of medication and more visits to the doctor or the emergency room. A．These particles are called PM 2.5. B．We divide particles into two major groups. C．These particles cause less severe health effects. D．Air pollution is a growing problem in the whole world. E．PM 2.5 can have worse health effects than the bigger PM 10. F．PM 10 particles can travel as little