in case万一。是连词，引导条件状语从句。也就是说incase后面是一个完整的句子 。in case of的of是介词，介词后面只能带名词性质的词，比如名词、代词等。意思和in case差不多，万一的意思。
用法例句
1. We have an auxiliary generator in case of power cuts.
我们有一台万一断电时使用的备用发电机。
2. In case you need something, please don&39;t hesitate to let me know.
如果你需要什么东西，请不客气地对我说。
3. It may rain you&39;d better take an umbrella (just) in case (it does).
可能下雨--你最好带把伞, 以防万一（下起来）.
4. In case that he leaves, please inform me.
如果他离开, 请通知我。
5. In case of rain, they can&39;t go.
万一下雨，他们就不能去了。
6. In case (=If) I forget, please remind me.
万一我忘记，请提醒我。
7. Write the telephone number down in case you forget.
把电话号码写下来以免忘了。
8. The doctor asked us to call him during the night except in case of necessity.
医生吩咐我们，除非必须，否则不要在夜里叫他。
可能下雨--你最好带把伞, 以防万一（下起来）.
4. In case that he leaves, please inform me.
如果他离开, 请通知我。
5. In case of rain, they can&39;t go.
万一下雨，他们就不能去了。
6. In case (=If) I forget, please remind me.
万一我忘记，请提醒我。
7. Write the telephone number down in case you forget.
把电话号码写下来以免忘了。
8. The doctor asked us to call him during the night except in case of necessity.
医生吩咐我们，除非必须，否则不要在夜里叫他。
