以防万一

yě xǔ bù xià yǔ bù guò hái shi dài bǎ sǎn yǐ fáng wàn yī

也许不下雨，不过还是带把伞，以防万一。

It may not rain, but you'd better take an umbrella just in case.

nǐ zài zhè fù jìn děng zhe yǐ fáng wàn yī tā lái le

你在这附近等着以防万一他来了。

You hang around here in case he comes.

dài bǎ qiāng yǐ fáng wàn yī

带把枪，以防万一。

As a precaution, take a gun with you.

tā men xié dài de xiàn jīn duō yú kāi zhī suǒ xū yǐ fáng wàn yī

他们携带的现金多于开支所需，以防万一。

They take more cash than they need in case anything should happen.