题目内容

SECTION B PASSAGES
Directions: In this section, you will hear several passages. Listen to the passages carefully and then answer the questions that follow.
听力原文: Any mistake made in the printing of a stamp raises its value to stamp collectors. A mistake on one cheap postage stamp has made the stamp worth a million and a half times its original value. The mistake was made more than a hundred years ago in the British colony 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 stamps.
Before the order was filled and delivered, a ball was planned at Mauritius Government House, and stamps were needed to send out the invitations. A local printer was instructed to copy the design for the stamps. He wrote by chance the words "Post Office" instead of "Post Paid" on the several hundred stamps that he printed.
Today there are only 26 of these wrongly printed stamps left I fourteen One Penny Orange-Reds and twelve Two Penny Blues. Because of the Two Penny Blue's rareness and age, collectors have paid as much as $16,800 for it.
In 1847 most countries of the world were

A. not yet using postage stamps.
B. collecting valuable stamps.
C. buying stamps from Mauritius.
D. printing their own stamps.

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更多问题

已知有10个进程共享一个互斥段,如果最多允许6个进程同时进入互斥段,则信号量S的初值为(26),信号量S的变化范围是(27)。

A. 0
B. 1
C. 5
D. 6

The best title for this passage is

A. The Discovery of Magellan's Strait
B. The Discovery of the Philippines
C. The Most Dangerous Expedition in Navigation
D. The First Expedition to Asia

关系代数运算是以集合操作为基础的运算,其五种基本运算是并、差、(57)、投影和选择,其他运算可由这些运算导出。为了提高数据的操作效率和存储空间的利用率,需要对(58)进行分解。

A. 交
B. 连接
C. 笛卡尔积
D. 自然连接

It can be inferred that

A. all correctly printed stamps are worthless.
B. Mauritius needed the stamps to send out invitations to a ball.
C. the printer was punished for his mistake.
D. collectors are constantly looking for stamps with mistakes.

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