You have an SQL query that takes one minute to execute. You use the following code segment to execute the SQL query asynchronously.Dim ar As IAsyncResult = cmd.BeginExecuteReader()You need to execute a method named DoWork() that takes one second to run while the SQL query is executing. DoWork() must run as many times as possible while the SQL query is executing. Which code segment should you use?()
A. While ar.AsyncWaitHandle Is Nothing DoWork()End Whiledr = cmd.EndExecuteReader(ar)
B. While Not ar.IsCompleted DoWork()End Whiledr = cmd.EndExecuteReader(ar)
C. While T hread.CurrentThread.ThreadState = ThreadState.Running DoWork()End Whiledr = cmd.EndExecuteReader(ar)
D. While Not ar.AsyncWaitHandle.WaitOne() DoWork()End Whiledr = cmd.EndExecuteReader(ar)
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文档管理包括().
A. 目录管理
B. 隐性知识管理
C. 知识分类和模块化机制
D. 知识地图和搜索机制
E. 内部文档的积累和更新机制
故障树分析中"最小割集"的概念是:()
A. 顶事件发生充分、必要的事件组合;
B. 顶事件不发生充分、必要的事件组合;
C. 结构重要性
D. 都不是