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The dogs that help in criminal investigations are trained at a school called the Military Dog Studies branch of the US Air Force in Lackland, Texas. The dogs to be trained are selected by an air force team. This team visits large cities across the country to buy dogs. They may buy dogs from private citizens for up to $ 750 each. Some citizens freely give their dogs. The dogs selected must be healthy, brave and aggressive. They must be able to fight back if they are attacked. The dogs chosen are between the ages of one and three. They are given a medical examination when they arrive at the school. Their physical examination includes X - rays and heart tests. The trainee dogs undergo the first stage of training when they arrive in Lackland. This is an 11 - week course for patrol duty. After this course, the best dogs are selected to go on another 9 - week course. They learn drug - sniffing or bomb - sniffing. After this course, the dogs are ready for their jobs in the cities or off air force bases.
Dogs are ready for their jobs of drug - sniffing or bomb - sniffing

A. after an 11 - week course.
B. after a 9 - week course.
C. after they are given medical examinations
D. after they have grown large enoug
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It is very difficult to say just when colonization began. The first hundred years after Christopher Columbus’s journey of discovery in 1492 did not produce any settlement on the North America continent but rather some Spanish trading posts further south, a great interesting gold and adventure, and some colorful crimes in which the English had their part. John Cabot, originally from Genoa but a citizen of Venice, was established as a trader in Bristol, England, when he made a journey in 1497. But his ship, the Matthew, with its crew of eighteen, did no more than see an island ( probably off the New England coast)and return home. He and his soft made further voyages across the north Atlantic which enabled the English crown to claim a legal title to North Americ
a. But for a long time afterwards the Europeans’ interest in America was mainly confined to the Spanish activities further south.
The first beginning of permanent settlement in North America were nearly a hundred years after Columbus’s first voyage. The English Sir Walter Raleigh claimed the whole of North America for England, calling it Virginia. In 1585 he sent a small group of people who landed in Roanoke Island, but they stayed only for a year and then went back to England with another expedition, led by Drake, in 1587. A second group who landed in 1587 had all disappeared when a further expedition arrived in 1590.
The first permanent settlement in North America was in 1607. English capitalists founded two Virginian companies, a southern one based in London and a northern one based in Bristol. It was decided to give the name New England to the northern area. The first settlers in Virginia were little more than wage slaves to the company. All were men and the experiment was not very successful many died. Those who survived lived in miserable conditions. By 1619 the colony had only a thousand people.A. The ancient Chinese.B. The ancient Egyptians.C. The ancient Babylonians.D. The ancient Indians.