阅读理解。 Notes: **API stands for Air Pollution Index(指数). **Particulate matter (PM10) is a major component of air pollution that threatens both our health and our environment. It consists of very small liquid and solid particles floating in the air. **Sulfur dioxide(SO2) acts as an acid．Inhalation(吸入) results in labored breathing, coughing, or a sore throat and may cause permanent lung damage. 1. According to Graph 1, which of the following cities has the worst air pollution? A. Qinhuangdao. B. Tianjin. C. Qingdao D. Shenyang. . 2. If your city is symbolized by either red or purple, the pollution in your city is _____. A. Moderate or high. B. Moderate or slight. C. Medium or high. D. Medium or slight. 3. Which of the following statements is TURE? A. With API value below 150 the air is free from being polluted. B. The colors from purple to Yellow indicate the air quality is becoming much worse. C. When there are floating solid particles and dust in the air, it is dangerous pollution. D. On September 8th the color-symbol of Beijing City's air quality is 'Blue'. 4. When more citizens are beginning to have labored breathing soon after they are in the open air, it suggests that _____. A. there is a large amount of sulfur dioxide in the air B. it is so cold that they may have caught a cold C. they are starting to cough or have a fever D. they must be infected with permanent lung disease