我刚刚付款给你了。

Wǒ gānggāng fùkuǎn gěi nǐ le.

I just paid you.

我可以用信用卡付款吗？

Wǒ kěyǐ yòng xìnyòngkǎ fùkuǎn ma?

May I use a credit card to pay?

我们只接收现金付款。

Wǒmen zhǐ jiēshōu xiànjīn fùkuǎn.

We only accept cash payment.