4 sentences

1. 要不然你早就离开她了。

   yào​bù​rán nǐ zǎo jiù lí​kāi tā le.

   Otherwise, you would've left her already.

   Source: OpenSubtitles

2. 我们快走吧，要不然就来不及了。

   wǒ​men kuài zǒu ba, yào​bù​rán jiù lái​bu​jí le.

   Let's go quickly, or it will be too late.

   Source: Dong Chinese Dictionary

3. 出门记得带把伞，要不然一会儿可能会淋雨。

   chū​mén jì​de dài bǎ sǎn, yào​bù​rán yī​huì​r kě​néng huì lín​yǔ.

   Remember to take an umbrella when you go out, otherwise you might get caught in the rain.

   Source: Dong Chinese Dictionary

4. 要不然你明天再来吧。

   yào​bù​rán nǐ míng​tiān zài lái ba.

   Otherwise, you should just come back tomorrow.

   Source: Dong Chinese Dictionary