万一
形容极小部分tiny part
非笔墨所能形容其万一。
It is completely beyond description.
意外变化eventuality
以备万一
in order to prepare for all eventualities
以防万一
in order to prepare for all eventualities
表示假设if by any chance
万一有什么事
if by any chance something happened
万一有什么意外，请马上通知我。
If anything unexpected happens, please let me know right away.
万一她不来，那怎么办？
If she does not come, what can be done?
