2 sentences for 证 (zhèng — certificate)

1. 因为忘带了证，他没法进入考场。

   yīn​wèi wàng dài le zhèng, tā méi​fǎ jìn​rù kǎo​chǎng.

   He couldn't enter the exam room because he forgot to bring his ID.

   Source: Dong Chinese Dictionary

2. 那家无证经营的工厂已被有关部门依法封闭。

   nà jiā wú zhèng jīng​yíng de gōng​chǎng yǐ bèi yǒu​guān bù​mén yī​fǎ fēng​bì.

   The unlicensed factory has been shut down by the authorities according to the law.

   Source: Dong Chinese Dictionary