2 sentences for 成人 (chéng​rén — reach adulthood)

1. 他独自一人把三个孩子抚养成人。

   tā dú​zì yī rén bǎ sān gè hái​zi fǔ​yǎng chéng​rén.

   He raised three children to adulthood on his own.

   Source: Dong Chinese Dictionary

2. 他已经成人，该为自己的行为负责了。

   tā yǐ​jīng chéng​rén, gāi wèi zì​jǐ de xíng​wéi fù​zé le.

   He is now an adult and should be responsible for his actions.

   Source: Dong Chinese Dictionary