习近平总书记曾经指出,创新驱动发展战略应从四个方向着手,其中不包括()
A. 把握正确方向
B. 聚集创新人才
C. 加大资金投入
D. 健全体制机制
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电压不但有大小,还有一定的方向,通常规定负电荷运动的方向为电压的方向。
A. 正确
B. 错误
You have an SQL query that takes one minute to execute. You use the following code segment to execute the SQL query asynchronously.IAsyncResult ar = cmd.BeginExecuteReader();You need to execute a method named Do Work() 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==null){DoWork();}dr=cmd.EndExecuteReader(ar);
B. while(!ar.IsCompleted){DoWork();}dr=cmd.EndExecuteReader(ar);
C. while(Thread.CurrentThread.ThreadState==ThreadState.Running){DoWork();}dr=cmd.EndExecuteReader(ar);
D. while(!ar.AsyncWaitHandle.WaitOne()){DoWork();}dr=cmd.EndExecuteReader(ar);
国家水准网是采用从整体到局部、由()、逐级布设、逐级加密的。按其布设密度和施测精度的不同分为一、二、三、四等
磨煤机主电机冷却水取自闭式水;
A. 正确
B. 错误