文档介绍：Part II prehension (35 minutes)
Directions: There are 4 reading passages in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A), B), C£© and D£©. You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the centre .
Passage 1
¡¡¡¡Toward the end of the 19th century scientists believed they were close to plete description of the universe. They imagined that space was filled everywhere by a continuous medium called the ether. Light rays and radio signals were waves in this ether just as sound is pressure waves in air. All that was needed plete the theory was careful measurements of the elastic properties of the ether; once they had those nailed down, everything else would fall into place.
¡¡¡¡Soon, however, discrepancies with the idea of an all-pervading ether began to appear. You would expect light to travel at a fixed speed through the ether. So if you were traveling in the same direction as the light, you would expect that its speed would appear to be lower, and if you were traveling in the opposite direction to the light, that its speed would appear to be higher. Yet a series of experiments failed to find any evidence for differences in speed due to motion through the ether.
¡¡¡¡But it was a young clerk named Albert Einstein, working in the Swiss Patent Office in Bern, who cut through the ether and solved the speed-of-light problem once and for all. In June 1905 he wrote one of three papers that would establish him as one of the world's leading scientists - and in the process start two conceptual revolutions that changed our understanding of time, space and reality.
¡¡¡¡In that 1905 paper, Einstein pointed out that because you could not detect whether or not you were moving through the ether, the whole notion of an ether was redundant. Instead, Einstein started from the postulate that the laws of science should appear the