3 sentences

1. 失物招领处在哪儿？

   shī​wù zhāo​lǐng​chù zài nǎ​r?

   Where is the lost and found?

   Source: Tatoeba

2. 请把捡到的失物交到前台。

   qǐng bǎ jiǎn​dào de shī​wù jiāo​dào qián​tái.

   Please hand in any found items to the front desk.

   Source: Dong Chinese Dictionary

3. 捡到失物后，应当及时返还给失主。

   jiǎn​dào shī​wù hòu, yīng​dāng jí​shí fǎn​huán gěi shī​zhǔ.

   After finding a lost item, it should be returned to the owner promptly.

   Source: Dong Chinese Dictionary