题目内容

发出如下命令： (a)grant select on hr.regions to jon; (b)grant all on hr.regions to jon; (c)grant dba to jon; (d)grant select on hr.regions to public; 哪些授权可以撤销以阻止JON看到HR.REGIONS的内容(选择所有正确的答案)？

A. (a)、(b)、(c)和(d)
B. (a)、(c)和(d)
C. (b)、(c)和(d)
D. (c)和(d)
E. (a)、(b)和(c)

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什么时候可以选择或更改数据库字符集(选择所有正确的答案)？

A. 如果没有使用任何模板，发生在创建数据库时
B. 如果使用不包含数据文件的模板，发生在创建数据库时
C. 无论用不用模板，都在创建数据库时发生
D. 创建数据库后(使用DBCA)
E. 创建数据库后(使用SQL*Plus)

打开数据库时，哪些文件必须被同步(选择一个最佳答案)？

A. 数据文件、联机重做日志文件以及控制文件
B. 参数文件和口令文件
C. 所有多重控制文件副本
D. 不需要同步任何文件，SMON进程会在打开数据库之后通过实例恢复来同步所有文件

设X，Y相互独立且都服从N(μ，σ2)，求E[min(X，Y)]．

How is urbanization negatively affecting our society Growing (1) is associated with urbanism. Urbanism (2) , urban violence, political instability, crime and (3) behavior. It also perpetuates poverty and (4) the traditional family structure. Other problems include failing (5) , safety, transportation, housing, education and electricity. (6) are much higher in urban areas. With divorce rates rising, (7) is becoming more of a problem than before. People are (8) by race, religious practices, (9) heritage, as well as economic and social status. This often creates much (10) and prejudice between social groups. This can cause physical or mental damage to individuals or (11) .The government assumes major (12) for development attempting to meet rapidly increasing demands for (13) , housing, transportation and employment. But they are not able to (14) all the problems in urban areas.America has hired approximately (15) more teachers in the last few years than have been hired in the past, but the increase in population keeps the (16) just as large. Due to the (17) in urban areas and the lack of (18) opportunity, the crime rate is still a huge problem. The problems in urban areas are far more (19) than can be handled in any (20) efforts. 16（）