3 sentences

1. 请把剩下的食物密封好。

   qǐng bǎ shèng​xià de shí​wù mì​fēng hǎo.

   Please seal the leftover food properly.

   Source: Dong Chinese Dictionary

2. 这是真空密封的。

   zhè shì zhēn​kōng mì​fēng de.

   This is vacuum-sealed.

   Source: OpenSubtitles

3. 这种名茶如果密封不好，其香气很容易走失。

   zhè zhǒng míng​chá rú​guǒ mì​fēng bù hǎo, qí xiāng​qì hěn róng​yì zǒu​shī.

   If this famous tea is not well-sealed, its aroma will easily dissipate.

   Source: Dong Chinese Dictionary