3 sentences

1. 我们所有的客人必须至少年满18岁。

   wǒ​men suǒ​yǒu de kè​ren bì​xū zhì​shǎo nián​mǎn18 suì.

   All of our guests must be at least 18 years of age.

   Source: CCMatrix

2. 您必须年满18岁并拥有自己的电脑。

   nín bì​xū nián​mǎn18 suì bìng yōng​yǒu zì​jǐ de diàn​nǎo.

   You must be at least 18 years old and own your own computer.

   Source: CCMatrix

3. 客人必须年满21岁，或由负责任的成人陪同。

   kè​ren bì​xū nián​mǎn21 suì, huò yóu fù zé​rèn de chéng​rén péi​tóng.

   Guests must be aged 21 or over, or accompanied by a responsible adult.

   Source: CCMatrix