Just in case: 万一
Raises an unlikely and unwelcome possibility, usually to justify a precaution. It is always hypothetical and never reports what happened.
Structure
万一 + 不希望发生的事，（就）+ … ｜ 预防措施，万一 + 情况 + 呢？
Explanation
Chinese words in this text can be activated to show a dictionary gloss.
，？ “Take an umbrella — what if it rains?” Literally “one in ten thousand”, raises a possibility the speaker thinks unlikely but does not want to be caught out by. It is the word of precautions, contingency plans and worried warnings.
Two shapes are common. As a condition, opens the first clause and the second says what to do or what would follow, often with : ， “If by any chance you can’t find the way, call me.” As a justification, the precaution comes first and + situation + follows as a short question: ，？
The event after is something you would rather did not happen. For a neutral or welcome condition — fine weather, a free afternoon — use . And because is hypothetical by nature, it cannot describe an event that has already taken place. When it ends a sentence as a question, the particle is , not : it is a “what if”, not a yes-or-no question.
Correct
Say each one out loud before moving on. The audio is a reference pronunciation, not a model to imitate exactly — match the tone contour, not the voice.
带上伞吧，万一下雨呢？帶上傘吧，萬一下雨呢？
Dàishang (fourth tone, falling) sǎn (third tone, dipping) ba, (neutral tone) wànyī (fourth tone, falling) xià (fourth tone, falling) yǔ (third tone, dipping) ne? (neutral tone)···
Take an umbrella — what if it rains?
万一找不到路，就给我打电话。萬一找不到路，就給我打電話。
Wànyī (fourth tone, falling) zhǎo (third tone, dipping) bú (second tone, rising) dào (fourth tone, falling) lù, (fourth tone, falling) jiù (fourth tone, falling) gěi (third tone, dipping) wǒ (third tone, dipping) dǎ (third tone, dipping) diànhuà. (fourth tone, falling)···
If by any chance you can’t find the way, call me.
我们早点儿出发吧，万一路上堵车就麻烦了。我們早點兒出發吧，萬一路上堵車就麻煩了。
Wǒmen (third tone, dipping) zǎo (third tone, dipping) diǎnr (third tone, dipping) chūfā (first tone, high and level) ba, (neutral tone) wànyī (fourth tone, falling) lùshang (fourth tone, falling) dǔchē (third tone, dipping) jiù (fourth tone, falling) máfan (second tone, rising) le. (neutral tone)···
Let’s set off a bit earlier — if we got stuck in traffic, it would be a real nuisance.
Incorrect — Common mistakes
These sentences are wrong. They are printed here on purpose, each one paired with the repair and the reason, because the error you can recognise is the error you stop making.
Not quite
Incorrect sentence: 万一明天天气很好，我们就去公园。
Correct
Correct sentence: 如果明天天气好，我们就去公园。
Why: 万一 raises an unwelcome possibility. Good weather is a neutral or welcome condition, so it takes 如果.
Not quite
Incorrect sentence: 我们昨天万一迟到了。
Correct
Correct sentence: 我们昨天迟到了。
Why: 万一 is always hypothetical. To report what happened, state it plainly.
Not quite
Incorrect sentence: 带上伞吧，万一下雨吗？
Correct
Correct sentence: 带上伞吧，万一下雨呢？
Why: “What if…?” takes 呢. 吗 asks a yes-or-no question, which is not what is being asked.
Compared with
Most errors with this pattern are not errors about this pattern — they are a neighbouring pattern arriving at the wrong moment. Read these side by side.
如果 introduces any condition with no attitude attached: 如果下雨，我们就不去了. 万一 colours the condition: it is unlikely, unwelcome, and worth guarding against. That is why 万一 so often justifies a precaution — 带上伞吧，万一下雨呢？ — while 如果 simply plans for alternatives. A welcome possibility (winning a prize, fine weather) never takes 万一.
If: 如果…（的话），就… →Mini quiz
Question 1 / 3Total score: 0
Fill the gap: 多带点儿钱吧，___ 不够用呢？