虚方法调用有什么重要作用?具有什么修饰符的方法不能够使用虚方法调用?
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磁盘碎片整理可以()。
A、合并磁盘空间
B、减少新文件产生碎片的可能
C、清理回收站的文件
D、检查磁盘坏扇区
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MODEM一词是()两词的综合体,中文译作【调制解调器】。其作用是实现电话线中的模拟信号与数字信号的互相翻译,从而实现个人计算机与ISP的互相通信。
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Which of the following datatypes store time-zone information in the database?()
A、 TIMESTAMP
B、 DATE
C、 TIMESTAMP WITH TIME ZONE
D、 TIMESTAMP WITH LOCAL TIME ZONE
E、 DATETIME
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You are creating a servlet that generates stock market graphs. You want to provide the web browser withprecise information about the amount of data being sent in the response stream. Which twoHttpServletResponse methods will you use to provide this information?()
Aresponse.setLength(numberOfBytes);
Bresponse.setContentLength(numberOfBytes);
Cresponse.setHeader(Length, numberOfBytes);
Dresponse.setIntHeader(Length, numberOfBytes);
Eresponse.setHeader(Content-Length, numberOfBytes);
Fresponse.setIntHeader(Content-Length, numberOfBytes);
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What are the prerequisites for performing flashback transactions? ()(Choose all that apply)
ASupplemental log must be enabled
BSupplemental log must be enabled for the primary key
CUndo retention guarantee for the database must be configured
D”EXECUTE “ permission on the DBMS_FLASHBACK package must be granted to the user