3 sentences

1. 他在台下练习了很久才上台表演。

   tā zài tái​xià liàn​xí le hěn jiǔ cái shàng​tái biǎo​yǎn.

   He practiced offstage for a long time before performing on stage.

   Source: Dong Chinese Dictionary

2. 他在台下深吸一口气，然后徐步走上台前。

   tā zài tái​xià shēn​xī yī kǒu qì, rán​hòu xú​bù zǒu​shàng tái qián.

   He took a deep breath offstage and then stepped slowly onto the platform.

   Source: Dong Chinese Dictionary

3. 那名武生走到台前，向台下的观众威风地一亮相。

   nà míng wǔ​shēng zǒu dào tái​qián, xiàng tái​xià de guān​zhòng wēi​fēng de yī liàng​xiàng.

   The martial arts actor walked to the front of the stage and struck an impressive pose for the audience.

   Source: Dong Chinese Dictionary