Hypothetical Compound: 万一...就... (In Case / Just in Case)
万一……，（就）……
Express unlikely but possible scenarios and prepare for worst-case situations using 万一...就...
Use 万一 to introduce an unlikely but possible scenario that should be prepared for. The second clause often contains a precaution or describes what would happen in that worst case. 万一 literally means "one in ten thousand."
万一 emphasizes that the situation is unlikely but still worth considering. It often carries a tone of warning or caution. Unlike 如果 and 假如, which are neutral about likelihood, 万一 specifically implies low probability. 就 is often used in the result clause but can be omitted.
Lesson Targets
Podcast
Podcast: Hypothetical Compound: 万一...就... (In Case / Just in Case) (万一……，（就）……)
Listen to Jason & Amy explain the 万一……，（就）…… pattern
New here?
Understanding 万一……，（就）……
The 万一...就... pattern is used to talk about unlikely scenarios that still need to be prepared for. The word 万一 literally means "one in ten thousand," reflecting the idea that the chance is very small but not zero. This structure is commonly used when giving warnings, making contingency plans, or explaining why precautions should be taken. For example, you might say 万一下雨怎么办？(What if it rains?) when planning an outdoor event. The pattern is extremely practical in everyday life — from travel planning to health precautions to business preparations. Unlike 如果 or 假如, which simply present a condition without implying probability, 万一 always suggests that the speaker considers the event unlikely but wants to be prepared just in case.
Key Points
- 万一 (wànyī) literally means "one in ten thousand" — it implies the condition is unlikely but possible.
- Used for warnings, contingency plans, and worst-case scenarios.
- Often paired with 就 in the result clause, but 就 can be omitted.
- 万一 can also be used alone as an adverb meaning "just in case": 带把伞吧，万一下雨呢。
- The tone is cautionary — speakers use 万一 to urge preparation or explain precautions.
- Cannot be replaced by 如果 without losing the "unlikely but possible" nuance.
Chinese culture places great value on being prepared (有备无患, yǒu bèi wú huàn — "preparedness averts peril"). The frequent use of 万一 in daily conversation reflects this cultural tendency to think ahead and plan for contingencies. Parents especially love using 万一 when advising their children: 万一迷路了怎么办？(What if you get lost?)
Key Vocabulary
Example Sentences
万一我没来，你就自己先去吧。
In case I do not come, just go ahead by yourself.
一定要把你们的护照带上，万一需要，没带就麻烦了。
Make sure to bring your passports — in case you need them, it would be troublesome not to have them.
万一路上堵车，我们就会迟到。
In case there is traffic on the road, we will be late.
你最好多带点儿钱，万一不够花呢。
You had better bring extra money, just in case it is not enough.
万一他不同意，我们就得想别的办法。
In case he does not agree, we will have to think of another way.
带把伞吧，万一下雨呢？
Bring an umbrella — what if it rains?
万一考试没通过，我就得再考一次。
In case I do not pass the exam, I will have to retake it.
Common Mistakes
万一 is only for unlikely or undesirable scenarios. Good weather is not a worst case — use 如果 instead.
就 must come after the subject. Correct word order: subject + 就 + predicate.
Practice Exercises
Tips & Tricks
Remember: 万一 = "one in ten thousand." Use it only for unlikely but still possible situations, usually undesirable ones.
A handy formula: 万一 + bad thing happens, 就 + what to do about it.
Compare the three "if" words: 如果 (neutral if), 假如 (formal/hypothetical if), 万一 (worst-case if).
When 万一 appears at the end of a sentence with 呢, it works as "what if...?": 万一下雨呢？
Homework
Write five sentences giving advice to a friend about to travel abroad. Use 万一 in each sentence to warn about unlikely but possible problems: losing a passport, missing a flight, getting sick, running out of money, and losing luggage.