3 sentences

1. 我想我在竞技场下面。

   wǒ xiǎng wǒ zài jìng​jì​chǎng xià​miàn.

   I think I'm under the arena.

   Source: OpenSubtitles

2. 运动员们走进了竞技场。

   yùn​dòng​yuán men zǒu​jìn le jìng​jì​chǎng.

   The athletes entered the arena.

   Source: Dong Chinese Dictionary

3. 让他们在竞技场里决斗吧。

   ràng tā​men zài jìng​jì​chǎng lǐ jué​dòu ba.

   Let them fight in the arena.

   Source: OpenSubtitles