a system for screening luggage in airports; an agent passes a swab around or inside luggage and then runs the swab through a machine that can detect trace amounts of explosives
同义词：explosive trace detection
详细解释：
ETD 或 e.t.d.abbr.（略语）Estimated time of departure.估计离开时间：估计出发的时间（预计离开的时间）