如果你不相信我，你可以问一下其他人。

Rúguǒ nǐ bù xiāngxìn wǒ, nǐ kěyǐ wèn yíxià qítā rén.

If you don't believe me, you can ask someone else.

如果你改变主意的话，记得要告诉我。

Rúguǒ nǐ gǎibiàn zhǔyì dehuà, jìde yào gàosu wǒ.

If you change your mind, remember to tell me.

如果你有什么问题，请随时联系我。

Rúguǒ nǐ yǒu shénme wèntí, qǐng suíshí liánxì wǒ.

If you have any problems, please contact me at any time.