2. 外语
  3. The vitamins necessary for a healthy body are normally supplied by a good mixed diet(饮食), including a variety of fruits and gree

The vitamins necessary for a healthy body are normally supplied by a good mixed diet(饮食), including a variety of fruits and gree

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问题     The vitamins necessary for a healthy body are normally supplied by a good mixed diet(饮食), including a variety of fruits and green vegetables. It is only when people try to live on a very restricted diet that it is necessary to make special provision to supply the missing vitamins.
    An example of the dangers of a restricted diet may be seen in the disease known as " beriberi" . It used to distress large numbers of Eastern peoples who lived mainly on rice. In the early years of this century, a scientist named Eijkman was trying to discover the cause of "beri-beri". At first he thought it was caused by a germ. He was working in a Japanese hospital, where the patients were fed on polished rice which had the outer husk(外壳)removed from the grain. It was thought this would be easier for weak and sick people to digest.
    Eijkman thought his germ theory was confirmed when he noticed the chickens in the hospital yard, which were fed on leftovers(剩饭)from the patients’ plates, were also showing signs of the disease. He then tried to isolate the germ, but his experiments were interrupted by a hospital official , who declared that the polished rice, even though left over by the patients, was too good for chickens. It should be recooked for the patients, and the chickens should be fed on cheap rice with the outer layer still on the grain.
    Eijkman noticed that the chickens began to recover on the new diet. He began to consider the possibility that eating unpolished rice somehow prevented or cured "beri-beri" —even that a lack of some element in the husk might be the cause of the disease. Indeed this was the case. The element needed to prevent " beri-beri" was shortly afterwards isolated from rice husks and is now
known as vitamin B. Nowadays, this terrible disease is much less common thanks to our knowledge of vitamins.
The chemical substance missing from polished rice______.
选项 A、was vitamin B
B、did not affect the chickens
C、was named the Eijkman vitamin
D、has never been accurately identified
答案A
解析 本题考查考生对细节的把握。根据文章最后一段倒数第二句可知，精米中所缺少的物质是维生素B。故选A。
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