3 sentences

1. 十几年后，四个孩子都已长大成人。

   shí jǐ​nián hòu, sì ge hái​zi dōu yǐ zhǎng​dà​chéng​rén.

   Years later all four children have grown up.

   Source: CCMatrix

2. 他们长大成人后，兄弟俩做了许多英雄壮举。

   tā​men zhǎng​dà​chéng​rén hòu, xiōng​dì liǎ zuò le xǔ​duō yīng​xióng zhuàng​jǔ.

   When they grew up, the brothers carried out many heroic deeds.

   Source: CCMatrix

3. 你们问他吧；他已经长大成人，能为自己说话了。

   nǐ​men wèn tā ba; tā yǐ​jing zhǎng​dà​chéng​rén, néng wèi zì​jǐ shuō huà le.

   Ask him; he is of age; he will speak for himself.

   Source: CCMatrix