短語詞組短語at half -mast (潛艇)露出半段通氣設備half -mast belay 半柱確保flag at half -mast 降半旗Half -mast The Flag 下半旗Flags at Half -mast 降半旗fly a flag at half -mast 降半旗;下半旗 返回 half-mast