2 sentences for 预演 (yù​yǎn)

1. 全体演员正在为明天的开幕式进行最后一次预演。

   quán​tǐ yǎn​yuán zhèng​zài wèi míng​tiān de kāi​mù​shì jìn​xíng zuì​hòu yī cì yù​yǎn.

   The whole cast is doing the final rehearsal for tomorrow's opening ceremony.

   Source: Dong Chinese Dictionary

2. 在正式任务开始前，团队在模拟环境中进行了多次技术预演。

   zài zhèng​shì rèn​wu kāi​shǐ qián, tuán​duì zài mó​nǐ huán​jìng zhōng jìn​xíng le duō cì jì​shù yù​yǎn.

   Before the official mission began, the team conducted several technical rehearsals in a simulated environment.

   Source: Dong Chinese Dictionary