题目

（8分）汽车原来以5m/s的速度沿平直公路行驶，刹车后获得的加速度大小为0.4m/s2则：（1）汽车刹车后经多少时间停止？滑行距离为多少？（2）刹车后滑行30m经历的时间为多少？停止前2.5s内滑行的距离为多少？ 答案：（1）由 得由 得（2）由 得解得或(舍去)根据运动对称性反向观察,In the summer of 1885, nine-year-old Joseph Meister was very ill. He had been attacked by a sick dog that had rabies(狂犬病), a very dangerous disease. His doctor tried to help him, but there was no cure for rabies at that time. The doctor told Joseph’s parents that perhaps there was one man who could save Joseph’s life. His name was Louis Pasteur.When Pasteur was young, he was especially interested in medicine, so he spent many hours every day with the chemist (药剂师）who lived in his small town. At that time, the chemist had to make all the medicines himself. Young Louis enjoyed watching the chemist as he worked and helped those people who came to him each day. Pasteur decided that one day he would help people, too.As a school boy, Pasteur worked slowly and carefully. At first, his teachers thought that young Louis might be a slow learner. Through elementary school, high school, and college, Pasteur worked the same way. In fact, he was not a slow learner, but a very intelligent young man. He became a college professor and scientist, and he continued to work very carefully.Because of Pasteur’s patience, he was able to make many observations and germs (细菌). Pasteur was studying about the germs that cause rabies when Joseph Meister became ill. In fact, Pasteur believed that he had a medical treatment for rabies, but he never gave it to a person before. At first, Pasteur was afraid to treat Joseph, but the doctor said the child was dying. Pasteur gave Joseph an inoculation (预防接种）every day for ten days. Slowly, the child became better.During his lifetime, Pasteur studied germs and learned how they cause diseases in animals and people and also studied the way to prevent diseases. On September 28, 1895，Louis Pasteur passed away. The work of this great man has been of great help to modern medicine.1.According to the passage, young Louis______.A. was badly hurt by a dogB. was very interested in medicineC. made a living by working for a chemistD. had been thought highly of his teachers2.We can learn from Paragraph 3 that Louis Pasteur_____.A. was always patient B. was clever but proudC. was a slow learner D. was a humorous professor3.The underlined word “it ”in Paragraph 4 refers to “_____”.A. the sick dog B. the medical treatment for rabiesC. the germ D. the poor child4.What would be the best title for the passage?A. Germs and Diseases B. Rabies: a Terrible DiseaseC. The Earliest Chemist D. Louis Pasteur: a Great Scientist