Expressing “What If” with “wànyī”

你还是先把资料备份一下吧，万一电脑出问题就麻烦了。

Nǐ háishi xiān bǎ zīliào bèifèn yíxià ba, wànyī diànnǎo chū wèntí jiù máfan le.

You had better back up the files first, because if the computer has a problem, it will be troublesome.

现在先别急着下结论，万一情况跟我们想的不一样呢？

Xiànzài xiān bié jí zhe xià jiélùn, wànyī qíngkuàng gēn wǒmen xiǎng de bù yíyàng ne?

Don’t rush to a conclusion now. What if the situation is not what we think?

出门最好带上身份证，万一需要用到的时候找不到就麻烦了。

Chūmén zuìhǎo dài shàng shēnfènzhèng, wànyī xūyào yòng dào de shíhou zhǎo bu dào jiù máfan le.

It is best to bring your ID when you go out, because if you need it and cannot find it, that will be troublesome.