Space Policy Directive-3 lays out general guidelines for the United States to mitigate the effects of space debris and track and manage traffic in space.
《空间政策指令3》为美国制定了一般性指南，以减轻空间碎片的影响以及跟踪和管理太空交通。
2
The entire sound track consists of three essential ingredients: the human voice, sound effects and music.
整个音轨由三个基本要素组成：人声、音效和音乐。
3
Three dozen NOAA vessels are currently working to track the oil spill and major research cruises are being put together to study the effects of the BP oil spill in the Gulf.