面授机宜 give on-site instructions
Explanation
指当面指示处理事务的方针、办法等。比喻现场指导，随机应变。
Refers to on-site instructions for handling matters. A metaphor for on-site guidance and the ability to improvise.
Origin Story
话说唐朝名将薛仁贵，征战沙场，屡建奇功。一次，他率军与敌军交战，战况异常激烈。薛仁贵身先士卒，冲锋陷阵，但敌军人数众多，一时难以取胜。这时，他发现敌军阵型出现漏洞，便立即命令副将率领一支精兵，从侧翼发起攻击，并亲自面授机宜，指导他们如何配合，如何攻其不备。副将领命而去，按照薛仁贵的指示，成功地突破了敌军的防线，打乱了敌军的部署，最终取得了战斗的胜利。薛仁贵之所以能取得这场战争的胜利，正是因为他临场指挥，面授机宜，充分发挥了将领的智慧和指挥能力。
It is said that Xue Rengui, the famous Tang Dynasty general, repeatedly achieved great feats in battle. Once, he led his army to fight against the enemy, and the battle was extremely fierce. Xue Rengui fought at the forefront, but the enemy army was superior in numbers and it was initially difficult to win. At this moment, he found a loophole in the enemy's formation and immediately ordered a deputy general to lead a crack force to launch a flank attack, and personally instructed them on how to coordinate and how to take the enemy by surprise. The deputy general received the order and, following Xue Rengui's instructions, successfully broke through the enemy's lines, disrupted the enemy's deployment, and ultimately achieved victory in the battle. The reason why Xue Rengui could win this battle was precisely because he commanded on the spot, giving personal instructions, and fully demonstrated his wisdom and commanding ability.
Usage
多用于军事或其他需要现场指挥的场合，表示现场指导，随机应变。
Mostly used in military or other occasions that require on-site command, expressing on-site guidance and improvisation.
Examples
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将军临阵面授机宜，士兵们奋勇杀敌。
jiangjun linzhen mianshuo jiyi, shibingmen fenyong shadi.
The general gave on-site instructions, and the soldiers fought bravely.
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经验丰富的老师面授机宜，学生们很快掌握了技能。
jingyan fengfu de laoshi mianshuo jiyi, xueshengmen henkuai zhangwo le jineng.
The experienced teacher gave personal instructions, and the students quickly mastered the skills.