7 sentences

1. 她年纪够大该懂事了。

   tā nián​jì gòu dà gāi dǒng​shì le.

   She is old enough to know better.

   Source: Tatoeba

2. 毛孩子不懂事，别跟他计较。

   máo hái​zi bù dǒng​shì, bié gēn tā jì​jiào.

   He's just an immature kid; don't take it personally.

   Source: Dong Chinese Dictionary

3. 这孩子懂事又听话，真招人疼。

   zhè hái​zi dǒng​shì yòu tīng​huà, zhēn zhāo rén téng.

   This child is so sensible and well-behaved; he’s truly endearing.

   Source: Dong Chinese Dictionary

4. 邻居们都赞他是个懂事的好孩子。

   lín​jū men dōu zàn tā shì gè dǒng​shì de hǎo hái​zi.

   The neighbors all praise him for being a sensible and good child.

   Source: Dong Chinese Dictionary

5. 这孩子非常懂事，从来不让父母操心。

   zhè hái​zi fēi​cháng dǒng​shì, cóng​lái bù ràng fù​mǔ cāo​xīn.

   This child is very sensible and never makes his parents worry.

   Source: Dong Chinese Dictionary

6. 看到孩子这么懂事，父母感到十分欣慰。

   kàn​dào hái​zi zhè​me dǒng​shì, fù​mǔ gǎn​dào shí​fēn xīn​wèi.

   Seeing their child so sensible, the parents felt very gratified.

   Source: Dong Chinese Dictionary

7. 经历了这些困难后，他变得懂事多了。

   jīng​lì le zhè​xiē kùn​nan hòu, tā biàn de dǒng​shì duō le.

   After going through these difficulties, he has become much more sensible.

   Source: Dong Chinese Dictionary