heavy material, such as gravel, sand, iron, or lead, placed in the bilge of a ship to ensure its stability
（碎石、沙、铁或铅等）压舱物。
a similar substance carried in an airship or on a hot-air balloon to stabilize it and jettisoned when greater altitude is required
（飞机或热气球保持稳定的）镇重物（升高时可抛弃）。
〈喻〉稳定因素；实质内容
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the film is an entertaining comedy with some serious ideas thrown in for ballast .这部影片是娱乐喜剧，添加了一些严肃有意义的内容压台。
gravel or coarse stone used to form the bed of a railway track or the substratum of a road
（作为铁道或公路路基的）道砟。
a mixture of coarse and fine aggregate for making concrete
（拌制混凝土的）石渣。
[count noun]a passive component used in an electric circuit to moderate changes in current
（电路中的）镇流器。
give stability to (a ship) by putting a heavy substance in its bilge
给（船）装压舱物。
form (the bed of a railway line or the substratum of a road) with gravel or coarse stone
给…铺道砟。
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in ballast （of a ship） laden only with ballast （船）只装有压舱物
" mid 16th cent.: probably of Low German or Scandinavian origin．"