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HSK 2.0 Level 5+ HSK 3.0 Level 5+ 6 min read

万一...（就）... for “In Case” and “What If”

Use 万一 for an unlikely, usually unwanted possibility and what to do if it happens.

Pattern

万一 + unlikely (unwanted) event，(就) + what to do / what will happen

万一 means “in the unlikely case that” or “what if.” It introduces something with a small chance of happening, usually something you don’t want, and the second clause (often with 就) says what to do or what would happen.

万一找不到路，就问一下别人。

When to use 万一...（就）... for “In Case” and “What If”

万一 literally means “one in ten thousand,” so it marks a small chance. Put it before the possible event, then give the plan or the result in the second clause, often with 就.

万一明天的火车晚点了，你就给我打电话。

In case tomorrow’s train is late, give me a call.

你最好把文件保存一下，万一电脑出问题就麻烦了。

You’d better save the file. It would be a real pain if the computer had a problem.

他万一不在家，我们怎么办？

What do we do if he happens not to be home?

带上伞吧，万一下雨呢？

Take an umbrella—what if it rains?

Common traps

  • Use 万一 for something unlikely and usually unwanted; for an ordinary or pleasant condition, use 如果 or 要是.
  • Don’t use 万一 for something that is sure to happen: say 到了以后给我打电话, not 万一到了给我打电话.
  • When the second clause is left out, the sentence usually ends with 呢: 带上伞吧，万一下雨呢？

Targeted drill

Practice this exact pattern before moving on.

你最好把文件保存一下， 电脑出问题就麻烦了

You’d better save the file. It would be a real pain if the computer had a problem
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