wàn yī
笔墨不能形容其万一。
bǐ mò bù néng xíng róng qí wàn yī.
Words cannot describe even one ten-thousandth of it.
多带几件衣服，以防万一。
duō dài jǐ jiàn yī fu, yǐ fáng wàn yī.
Bring a few extra pieces of clothing, just in case.
万一下雨也不要紧，我带着伞呢。
wàn yī xià yǔ yě bú yào jǐn, wǒ dài zhe sǎn ne.
It doesn't matter if it rains, I have an umbrella with me.