公司规定不能私自把文件带回家。

Gōngsī guīdìng bùnéng sīzì bǎ wénjiàn dài huíjiā.

The company rules state that you must not take documents home without permission.

学生不得私自离开校园，否则要通知家长。

Xuéshēng bùdé sīzì líkāi xiàoyuán, fǒuzé yào tōngzhī jiāzhǎng.

Students must not leave the campus without permission; otherwise their parents will be informed.

任何人都不能私自修改合同内容。

Rènhé rén dōu bùnéng sīzì xiūgǎi hétóng nèiróng.

No one is allowed to change the contract terms on their own.