| 阅读理解。 |
| One of nature's most remarkable effects is the mirage. Mirrages occur when there is a great difference in temperature between one layer of air in the atmosphere and the next. On a hot day, light rays from the sky. hit the unusually hot air just above pavement or sand. These rays bend and then continue horizontally along the line of vision, giving the illusion that a body of water lies ahead. Sometimes sailors in northern seas observe ships or icebergs seemingly hanging upside down in the sky. In this case, the warmer air lies above cooler, denser air. The warm air above reflects the image of the distant ship or iceberg, even when the same object is not seen directly because of atmospheric density. Between the coast of Italy and the island of Sicily lies the Strait of Messina. For centuries sailors have seen there the mirage of a whole city; this mirage is known as the fatal marriage (命运注定的婚姻). Scientists believe that some of the flying saucers that have been reported in many parts of the United States were actually mirages. When light rays are reflected at night by the warm air above the earth, the mirage of a lighted object appears in the sky. |
| 1. The body of water seen ahead while driving on a hot day is a ______. |
| A. body of water B. reflection of light rays from the sky C. reflection of a body of water D. reflection of sand |
| 2. Sailors in northern seas have observed mirages of ______. |
| A. bodies of water B. flying saucers C. ships or icebergs ahead D. ships or icebergs upside down in the sky |
| 3. Scientists believe that mirages can give a reason for ______. |
| A. none of the flying saucer reports B. some of the flying saucer reports C. most of the flying saucer reports D. all of the flying saucer reports |