有些函数需要使用系统调用来完成其工作，其它函数则不需要。
Some functions need to use a system call in order to do their work, others do not.
在一些地方，这种称为“白色空间”的用来隔离工作频道的未使用的频率最多占到电视转播中可用带宽的70%。
In some places, this so-called "white space" of unused frequencies separating working channels amounted to as much as 70% of the total bandwidth available for television broadcasting.
—data用来详细说明将要使用的工作区的位置。
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