The soldiers all used to do a six-month tour of duty in Northern Ireland.

士兵过去都要在北爱尔兰服役六个月。

《牛津词典》

IDA assigns sailors in the US navy to new jobs when they finish a tour of duty and has to juggle naval policies, job requirements, changing costs and sailors' needs.

当美国海军水兵完成他们的值勤的时候，艾达负责给他们分配新的任务，并且必须合理协调海军政策、工作需求、替换成本和水兵需要。

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We see those same qualities today, particularly in our young men and women in uniform who have served tour after tour of duty to defend our nation in harm’s way, and their civilian counterparts.

今天我们还可以看到美国人民的这些素质，尤其是穿着军装的年轻男女以及他们的文职伙伴，他们完成了一个又一个任务，为的就是保卫我们的国家免于危害。

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