具有时效性的即按即说 push-to-talk ; PTT
如果日历上没有明确的时间和日期，它就是一个不具有时效性的任务。
If there is not date and time of day on the calendar, it is not Time-based.
争议的信息必须是收集起来代价昂贵并且具有时效性。
The information in question must be expensive to gather and time sensitive.
由于亲属探监具有时效性，电话沟通需要监护人员的监听，因而这两种联系方式不能被大量使用。
Because the relative visits prisoners to have the effectiveness, the telephone communication needs the guardianship personnel's monitor, thus these two contact method cannot use massively.
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