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.

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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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上覆岩层对采动岩体活动全部或局部起决定性作用，上覆岩层运动是一个复杂的时空过程，具有时效性。

In the local or global movement of rock mass under mining, overlying strata play a key role. The overlying strata movement is a complicated space-time process and has time-dependent feature.

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