Can I help you, sir?  先生，我可以为您服务吗？

Yes, I want to buy some grapes.  是的，我想买一些葡萄。

What kind of grapes do you want?  您要哪种葡萄？

People say grapes from XinJiang are much sweeter than other kinds. Please give me a kilo of that.
人们说新疆的葡萄比其它种甜得多。请给我一公斤那个。

Ok, wait a moment please.  好的，请稍等。

Make sure they are fresh.  要确保是新鲜的。

Trust me.  相信我。