短語(yǔ)詞組短語(yǔ)official in lower echelon 下級(jí)官員officials in lower echelon 下級(jí)官員fly in echelon 梯隊(duì)飛行squadron in echelon 梯次配置的中隊(duì)flying in echelon 成梯隊(duì)飛行fly in echelon formation 梯次編隊(duì)飛行overall enrichment in echelon 梯次綜合富集aircraft flying in echelon 成梯隊(duì)飛行的飛機(jī) 返回 in echelon