须

• ピンイン: xū
• 漢字の分解: 须 = 彡 (hair strokes) + 页 (head) — originally beard; classical extension to 'necessity'

意味

（文語・公的）〜しなければならない

A formal auxiliary used in official documents, regulations, and literary writing to indicate that something is required or obligatory. Stronger and more formal than 需要 in written registers.

例文

1. 参加本次考试者须提前三十分钟到达考场并凭有效证件入场。
2. 合同双方须在协议生效前完成全部法律审核程序，否则协议无效。
3. 工程施工期间须严格遵守安全规程，任何违规行为将依规处理。

使い方ガイド

場面: law, regulations, official documents, academic

トーン: authoritative

正しい言い方

• 申请人须在截止日期前提交完整材料，逾期将不予受理。(Applicants must submit complete documents before the deadline; late submissions will not be accepted.)
• 所有设备须经过专业人员检验合格后方可投入使用。(All equipment must pass professional inspection before being put into service.)

避ける言い方

• 我须去买东西 — 须 is formal/written; use 需要 or 得 in everyday speech; 须 in casual contexts sounds stiff and archaic

起源と歴史

须 originally depicted beard hair (面部须毛), extended to mean 'necessarily/must' through classical usage

文化的背景

時代: Classical to Modern

世代: All ages

社会的背景: Universal