把查询语句的各个子句按执行的先后顺序排列,正确的是( )
A. FROM→WHERE→GROUP BY→SELECT→ORDER BY
B. SELECT→FROM→WHERE→GROUP BY→ORDER BY
C. WHERE→FROM→SELECT→GROUP BY→ORDER BY
D. FROM→WHERE→SELECT→ORDER BY→GROUP BY
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在T-SQL语言ORDER BY子句中,使用( )可以实现对查询结果升序排列。
A. DESC
B. ASC
CASE
D. TOP
已知三阶矩阵A的特征值是0,-2, 2,则下列结论不正确的是()
A. 矩阵A不可逆
B. 矩阵A的主对角线上元素之和是0
C. 特征值2与-2的特征向量是正交的
D. Ax=0的基础解系由一个向量组成
Different schools handle mealtimes in different ways. Some schools early care in the morning. These schools usually provide for their students. Other schools often provide an in-class in the late morning. Do your best to keep the school from giving students food. Young children need small, snacks throughout the day.不同的学校以不同的方式安排用餐时间。一些学校提供早托。这些学校通常给学生提供早餐。还有一些学校在上午晚些时候提供课堂点心。尽量让学校避免给学生吃垃圾食品。小孩子一整天都需要健康的小点心。
Computer (1) is an intrusive (2) that infects computer (3) by inserting (4) ofitself in those files. The copies are usually executed when the file is loaded into (5),allowing them to (6) still other files, and so on. Viruses often have damaging side effectssometimes intentional, sometimes not--such as destroying a computer's hard (7) or taking up(8)space that could otherwise be used by program.Avirus is a program, made by either a (9) or not. It is not so easy to make one, butmany people know how to do it, for example, you may know that you have to know some exact computer (10) to make a computer virus.