图示为一个储油圆柱桶，其底面直径与桶高相等。当桶中无油时，贴着桶的上边缘上的A点恰能看到桶底边缘上的B处；当桶内油的深度等于桶高的一半时，眼所处的位置不变，在桶外沿AB方向看去，恰能看到桶底上的C点，且BC的距离是桶底直径的四分之一(A、B、C三点在同一竖直平面内且BC在同一条直径线上) 。据此可估算出该油的折射率n和光在这种油中的传播速度v分别为(已知真空中的光速c=3×108 m/s)
A．1.6、1.6×108 m/s
B．2.2 、2.2×108 m/s
C．2.0、1.6×108 m/s
D．1.6、1.9×108 m/s
答案：D
| 完形填空 | |||
| There was once a lonely girl who wanted love very much. One day while she was walking in the forest, she found two birds. She took them home and put them in a small 1 . She was happy to have two "friends". She 2 them with love and the birds grew strong. One day the girl forgot to close the door of the cage. The 3 of the two flew out of the cage. The girl was afraid that it would fly away. She caught it quickly. She felt glad that she caught the bird before it could fly away. Suddenly she couldn't 4 a sound from the bird. When she opened her hand, the bird was already(已经) dead. Her 5 killed(杀死) the bird! Then she saw 6 bird jumping up and down 7 the cage. She could feel its great need for freedom. It wanted to fly into the blue sky. So she let it fly away 8 . The bird circled(转圈) once, twice, and three times. The girl 9 as the bird flew. She didn't care about losing the bird any more. She wanted it to be happy. Suddenly the bird flew closer and landed softly on her shoulder. It sang the 10 song she had ever heard (她所听过的). The fastest way to lose love is to hold it too tightly, and the best way to keep love is to give it wings. | |||
| ( )1. A. box ( )2. A. looked for ( )3. A. stronger ( )4. A. listen ( )5. A. love ( )6. A. one ( )7. A. outside ( )8. A. sadly ( )9. A. watched ( )10.A.worst | B. basket B. looked at B. lazier B. make B. joke B. the other B. inside B. happily B. saw B. oldest | C. cage C. looked after C. weakest C. describe C. luck C. another C. beside C. loudly C. looked C. newest | D. bag D. looked over D. smallest D. hear D. wish D. other D. behind D. highly D. heard D. sweetest |