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问题 单项选择题

患者，男， 岁，喜食巧克力，右下颌第一恒磨牙刚萌出，已见窝沟浅龋。医生向家长宣传饮食管理的概念，不正确的是

A．提示家长不过多地让儿童摄取蔗糖

B．饮料是流动性的液体，不易引起龋齿

C．控制点心和零食的次数和量

D．不宜偏食

E．不宜单侧咀嚼

答案

参考答案：B

填空题

三层交换机是一种用______实现的高速路由器。
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单项选择题

D


Any mistake made in the printing of a stamp raises its value. A mistake on one inexpensive postage stamp has made the stamp worth a million and a half times its original (本来的) value. The mistake was made more than a hundred years ago in the British colony (殖民地)of Mauritius, a small island in the Indian Ocean. In 1847 an order for stamps was sent to a London printer—Mauritius was to become the fourth country in the world to issue (发行) stamps.
Before the order was delivered(传达), a party was planned at Mauritius’Government House, and stamps were needed to send out the invitations. A local printer was told to copy the design for the stamps. He printed the words " Post Office " instead of " Post Paid " by mistake on the several hundred stamps that he printed.
Today there are only twenty-six of these misprinted stamps left—fourteen Onepenny Orangereds and twelve Twopenny Blues. Because of the Twopenny Blue’s rareness (稀少) and age, collectors have paid as much as $ 16800 for it.

The best title for this selection is ______.

A．The "Post Office" Mistake

B．The Twopenny Blue

C．A London Printer’s Mistake

D．How Maurius Became Famous
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