第一句：Could you help me find its owner?

您能帮我找到失主吗？

A: What can I do for you, sir?

先生，能为您做点什么？

B: I found this watch in the street. I guess it’s lost. Could you help me find its owner?

我在街上检到了这只手表。我想是谁丢的吧，您能帮我找到失主吗？

A: We'll try our best.

我们会尽力的。

第二句：I want to hand in a purse. I found it on a bus.

扰一下，我想上交一个钱包，我在公交车上捡到的。

A: I want to hand in a purse. I found it on a bus.

扰一下，我想上交一个钱包，我在公交车上捡到的。

B: OK. May I have your name, please?

好的，请问您叫什么名字？

其他表达法：

I found this wallet on the street.

我在街上捡到了这个钱包。