4 sentences

1. 几天后，他的伤口终于封口了。

   jǐ tiān hòu, tā de shāng​kǒu zhōng​yú fēng​kǒu le.

   After a few days, his wound finally closed up.

   Source: Dong Chinese Dictionary

2. 他在信封的封口处贴了透明胶带。

   tā zài xìn​fēng de fēng​kǒu chù tiē le tòu​míng jiāo​dài.

   He put transparent tape on the seal of the envelope.

   Source: Dong Chinese Dictionary

3. 由于受到了威胁，他只能选择封口。

   yóu​yú shòu​dào le wēi​xié, tā zhǐ néng xuǎn​zé fēng​kǒu.

   Being threatened, he had no choice but to stay silent.

   Source: Dong Chinese Dictionary

4. 这个方案已经封口，不再接受任何改动。

   zhè​ge fāng'àn yǐ​jīng fēng​kǒu, bù zài jiē​shòu rèn​hé gǎi​dòng.

   This plan is finalized and no further changes will be accepted.

   Source: Dong Chinese Dictionary