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  3. What does February 29th mean to you? For most people it means an extra day a

What does February 29th mean to you? For most people it means an extra day a

游客2023-10-15  81
问题     What does February 29th mean to you? For most people it means an extra day at work, which might explain why a leap year is generally considered to be unlucky. This is particularly so for those who only have the chance to celebrate their real birthday once every four years.

    【B1】______The first attempt at rationalizing the calendar was made by the ancient Egyptians over two thousand years ago. Having worked out that there were 365 days in a year they realized that every fourth year would need 366 days and set up their calendars accordingly. It was another two hundred years or more before the Romans, under Julius Caesar, settled upon February as the month to which the extra day should be added.
    【B2】______This is due to the fact that there are six hours left over from a strictly 365-day year. The rotation of the Earth around the sun, though predictable as far as orbit and gravity are concerned, is not as fixed as might be assumed as other factors, such as the effect of massive earthquakes, must be taken into account.
    【B3】______The ancient Egyptians set the ball rolling by developing early versions of the sundial. Later timekeepers included burning candles and water flowing through measurable holes. Perhaps surprisingly, the first hourglass to use the flow of sand did not appear until medieval times. Nevertheless, measuring time remained a relatively inexact science and it was not until the invention of the pendulum clock in the seventeenth century that it became more accurate.
    【B4】______the lack of precision in measuring hours and minutes created problems in the maritime sector. Sailors the world over had difficulty establishing exactly where they were at sea e-ven though they were able to use the sun and stars to guide them. The invention of reliable, sea-going clocks in the eighteenth century enabled sea-farers to calculate their longitude. This, coupled with knowledge of their latitude, took the guesswork out of pinpointing their position. Such advances meant that exploration of the oceans and trade by sea could flourish.
    【B5】______The fact that these two clocks used different measuring systems meant that eventually they showed different times. As a result of this, in the 1970s scientists corrected the discrepancy by introducing the leap second. However, it is not needed every year—the last leap second was on 1st January 2006. Nevertheless, in spite of the advances in timekeeping the difficulty of measuring time with faultless precision has not been completely resolved.
    The US has proposed using the atomic clock exclusively to measure world time thereby making the older timekeeping systems and leap seconds themselves redundant. If this method was adopted it would mean that time would no longer be measured by the rising and setting of the sun. However, there is some resistance to the idea as it is claimed that we would run the risk of being out of step with the rhythms of the planet’s natural cycle.
Questions 61 -65: Choose from the sentences A - G the one which best fits each gap of 61 - 65. There are two extra sentences which you do not need to use.
A. Apart from difficulties in measuring years and months with accuracy, which had an effect on the development of agriculture.
B. When early man began to farm the land, an understanding of how to measure time rapidly became a priority.
C. The earthquakes sometimes affect the relevant calculations of calendar.
D. Leap years are no new phenomenon.
E. In the 1950s the invention of the atomic clock revealed that timekeeping based on the movements of the Earth was less accurate than that based on vibrating atoms.
F. For us a leap year simply means that we have to work an extra day in February.
G. A calendar which, relies on the cycles of the sun is bound to run into trouble sooner or later, experts agree. [br] 【B4】
选项
答案 A
解析 上文提到农业发展的需要使得古人采用多种方法来测量时间，而下文讲述了无法准确测量小时和分钟对航海方面所产生的影响。A项“除了准确测量年份和月份存在困难，而对农业的发展造成影响外”起到承上启下的作用。
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