Federal law requires the government to conduct a nationwide test at least every three years.

联邦法律要求政府至少每三年进行一次全国性的测试。

This is the third time FEMA has conducted a wireless nationwide test of all cell phone emergency alerts but a second test to all cellular devices.

这是联邦应急管理局第三次在全国范围内对所有手机紧急警报进行无线测试，但第二次是对所有蜂窝设备进行测试。

For FEMA, the nationwide test is a chance to make sure the federal government can alert the entire country in the event of a nationwide emergency.

对联邦应急管理局来说，全国范围的测试是确保联邦政府能够在全国性紧急情况发生时向全国发出警报的机会。