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{{B}}The
Body Clock{{/B}} Why is it that flying to New York from London will leave you feeling less tired than flying to London from New York The answer may be a clear case of biology not being able to keep up with technology. Deep inside the brain there is a "clock" that governs every aspect of the body’s functioning: sleep and wake cycles, levels of alertness, performance, mood, hormone levels, digestion, body temperature and so on. It regulates all of these functions on a 24-hour basis and is called the biological clock. This body clock programmes us to be sleepy twice a day, between 3-5 am and again between 3-5 pm. Afternoon tea and nap are all cultural responses to our natural biological sleepiness in the afternoon. One of the major causes of the travellers’ malady known A. "condition". B. "discomfort". C. "injury". D. "excitement". 更多"{{B}}第三篇{{/B}}"的相关试题: [单项选择]第三篇
Water
The second most important constituent (构成成份) of the biosphere (生物圈) is liquid water. This can only exist in a very narrow range of temperatures, since water freezes at 0℃ and boils at 100℃. Life as we know it would only be possible on the surface of a planet which had temperatures somewhere within this narrow range.
The earth’s supply of water probably remains fairly constant in quantity. The total quantity of water is not known very accurately, but it is about enough to cover the surface of the globe to a depth of about two and three-quarter kilometers. Most of it is in the form of the salt water of the oceans about 97 percent. The rest is fresh, but three quarters of this is in the form of ice at the Poles and on mountains, and cannot be used by living systems until melted. Of the remaining fractional which is somewhat less than one per cent of the whole, there is 10—20 times as much stored underground water as t
A. in the center of the earth. B. on the surface of our planet. C. in a very narrow range of temperatures. D. in the coastal areas of the earth. [单项选择]{{B}}第三篇{{/B}}
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