在某些操作系统上，对任一时间内可拥有图像的数量有严格限制，因此使用它们时必须注意这一限制。
On some operating systems, there is a strict limit on the number of images you can have at any one time, so you must be aware of this restriction when using them.
选出待分派的作业或任务。在某些操作系统中，其它作业单位，诸如输入输出操作，也可被调度。
To select jobs or tasks that are to be dispatched. In some operating systems, other units of work such as input-output operations may also be scheduled.
在某些操作系统下，具有最高优先级(相对于可执行线程而言)的线程经过调度后总是首先运行。
Under some operating systems, the thread with the highest priority (of those threads that can be executed) is always scheduled to run first.
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