我的腿有点酸。

Wǒ de tuǐ yǒudiǎn suān.

My leg is a little sore.

我的腰好酸哦！

Wǒ de yāo hǎo suān o!

My back is so painful!

这个橙子很酸，我吃不下。

Zhè gè chéngzi hěn suān, wǒ chī bùxià.

This orange is very sour, I can't eat it.