年久的弹头到了2008年将达到设计的30年使用期，这些旧弹头也就在没有危害国家的核屏蔽的情况下被淘汰。
The older warheads, the most elderly of which will reach the end of their 30-year design lifespan in 2008, could then be retired without compromising the country's nuclear shield.
侯爽，钢筋混凝土结构预期使用期可靠度设计与FRP加固监测。
RC Structure Reliability Design for Expected Service Life and Its FRP Strengthening and Monitoring.
公园最初有一年的设计时间，后来讨论延长至五年，为了让公园达到永久的使用期。
The park was originally planned for a temporary period of one year, but it is still there five years after and there is an ongoing discussion to make the park permanent.
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