三．阅读理解：（20×2.5=50分） People have smoked cigarettes for a long time. The tobacco used to make cigarettes was grown in what is now part of the United States. Christopher Columbus, who discovered America, saw the Indians smoking, and soon the dried leaves were transported to Europe where smoking began to catch on. In the late 1800s, the Turk(土耳其人) made cigarettes even popular. Cigarettes smoke contains at least two harmful substances, tar and nicotine. Tar, which forms as the tobacco burns, damages the lungs and therefore affects breathing. Nicotine, which is found in the leaves, causes the heart to beat faster and increases breathing rate. Smoking cigarettes is erous. The U.S. Public Health Service stated that cigarette smoking is the cause of lung cancers and several other deadly diseases. The U.S. government now requires that each package of cigarettes bear（带有）a special warning about the er of smoking. 1. The expression “catch on” in the passage may mean _________. A. start B. cost a lot C. become popular D. erous 2. Before Columbus discovered America __________. A. Europeans had smoked B. Nobody smoked in the world C. Nicotine was not in tobacco D. Europeans had never smoked 3. In the nineth century smoking became popular because of the people in ________. A. India B. Turkey C. the U.S. D. British 4. Breathing is affected by ___________. A. nicotine B. tar C. heat D. both A and B