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在创建表文件时要定义一个日期型字段，应在该字段的宽度位置输入______。
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下面有关视图的叙述中错误的是______。
有如下主题帖表和回复帖表： 主题帖(编号C,用户名C,标题C,内容M,发帖时间T) 回复帖(编号C,用户名C,内容M,回复时间T,主题帖编号C) 统计并显示回复帖数量大于等于5的主题帖信息，正确的SQL语句是______。
有三个关系表R、S和T如下，其中三个关系对应的关键字分别为A，B和复合关键字(A，B)。 R A A1 a 1 b n S B B1 B2 f g h l x y n p x T A B C a f 3 b q 4 表T的记录项(b，q，4)违反了______。
A "LOST TRIBE" that reached America from Australia may have been. the first Native Americans, according to a new theory. (46)If proved by DNA evidence, the theory will shatter long established beliefs about the southerly migration of people who entered America across the Bering Strait, found it empty and occupied it.On this theory rests the authority of Native Americans (previously known as Red Indians) to have been the first true Americans. They would be relegated to the ranks of also-rans, beaten to the New World by Aboriginals in boats. To a European, this may seem like an academic argument, but to Americans it is a philosophical question about identity, Silvia Gonzales of Liverpool John Moores University said. Her claims are based on skeletons found in the Baja California Peninsula of Mexico that have skulls quite unlike the broad Mongolian features of Native Americans. These narrow-skulled people have more in common with southern Asians, Aboriginal Australians and people of the South Pacific Rim. (47)The bones, stored at the National Museum of Anthropology in Mexico City, have been carbon-dated and one is 12,700 years old, which places it several thousand years before the arrival of people from the North."We think there were several migration waves into the Americas at different times by different human groups," Dr. Gonzales said. "The timing, route and point of origin of the first colonization of the Americas remains a most contentious topic in human evolution." (48)But comparisons based on skull shape are not considered conclusive by anthropologists, so a team of Mexican and British scientists, backed by the Natural Environment Research Council, has also attempted to extract DNA from the bones.(49)Dr. Gonzales declined yesterday to say exactly what the results were, as they need to be checked, but indicated that they were consistent with an Australian origin.(50)She believes that they arrived by boat, settled in what is now Mexico and at other points along the Pacific coast, and survived for thousands of years.The first Spanish colonists and missionaries described the people they found in the area, the Pericue, as slim hunter-gatherers. They lacked much culture, but did have burial customs in which bodies were laid out in the sun before being painted with ochre and buried. The Spanish collected the people into missions, where they died out in the 18th century.
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