6 sentences

1. 未经许可，不得擅自进入。

   wèi jīng xǔ​kě, bù dé shàn​zì jìn​rù.

   No entry without permission.

   Source: Dong Chinese Dictionary

2. 游客不得擅自跨越国境。

   yóu​kè bù dé shàn​zì kuà​yuè guó jìng.

   Tourists are not allowed to cross the national border without authorization.

   Source: Dong Chinese Dictionary

3. 未经许可，不得擅自入内。

   wèi jīng xǔ​kě, bù dé shàn​zì rù​nèi.

   No entry without permission.

   Source: Dong Chinese Dictionary

4. 你不该让她擅自行动的。

   nǐ bù gāi ràng tā shàn​zì xíng​dòng de.

   You shouldn't have let her go rogue.

   Source: OpenSubtitles

5. 她为什么不过问你就擅自做这些事？

   tā wèi​shén​me bù guò​wèn nǐ jiù shàn​zì zuò zhè​xiē shì?

   Why does she do these things without asking you?

   Source: OpenSubtitles

6. 未经许可，任何人不得擅自进入实验室。

   wèi​jīng xǔ​kě, rèn​hé rén bù dé shàn​zì jìn​rù shí​yàn​shì.

   No one is allowed to enter the laboratory without permission.

   Source: Dong Chinese Dictionary