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【简答题】
某班有50位学生，每位学生一个序号，将50张编有学生序号（从1号到50号）的卡片（除序号不同外其它均相同）打乱顺序重新排列，从中任意抽取1张卡片． （1）在序号中，是20的倍数的有：20，40，能整除20的有：1，2，4，5，10（为了不重复计数，20只），求取到的卡片上序号是20的倍数或能整除20的概率； （2）若规定：取到的卡片上序号是k（k是满足1≤k≤50的整数），则序号是k的倍数或能整除k（不重复计数）的学生能参加某项活动，这一规定是否公平？请说明理由； （3）请你设计一个规定，能公平地选出10位学生参加某项活动，并说明你的规定是符合要求的．
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A.
each nation is peculiar enough to enable us to distinguish it from others
B.
the peoples of the world are as alike as they are different
C.
the peoples of the world have more similarities than differences
D.
those who do．more than is strictly necessary are common in every country
【多选题】Which two statements are true regarding single row functions?（）
A.
They accept only a single argument
B.
They can be nested only to two levels
C.
Arguments can only be column values or constants
D.
They always return a single result row for every row of a queried table
E.
They can return a data type value different from the one that is referenced
【单选题】根据以下内容回答题： Each nation has its own peculiar character which distinguishes it from others．But the peo-pies of the world have more points in common than points in which they differ．One type of per-son t...
A.
each nation is peculiar enough to enable us to distinguish it from others
B.
the peoples of the world are as alike as they are different
C.
the peoples of the world have more similarities than differences
D.
those who do．more than is strictly necessary are common in every country
【简答题】水的折射率20°C时为( ),25°C时为( )。
【多选题】Which three statements are true regarding single-row functions？（）
A.
They can accept only one argument.
B.
They can be nested up to only two levels.
C.
They can return multiple values of more than one data type.
D.
They can be used in SELECT， WHERE， and ORDER BY clauses.
E.
They can modify the data type of the argument that is referenced.
F.
They can accept a column name， expression， variable name， or a user-supplied constant as arguments.
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