3 sentences

1. 别那么小儿科，大方一点吧。

   bié nà​me xiǎo'ér​kē, dà​fang yī​diǎn ba.

   Don't be so childish; be more generous.

   Source: Dong Chinese Dictionary

2. 他在医院的小儿科当医生。

   tā zài yī​yuàn de xiǎo'ér​kē dāng yī​shēng.

   He is a doctor in the pediatrics department of the hospital.

   Source: Dong Chinese Dictionary

3. 修理这台电脑对他来说简直是小儿科。

   xiū​lǐ zhè tái diàn​nǎo duì tā lái shuì jiǎn​zhí shì xiǎo'ér​kē.

   Repairing this computer is child's play for him.

   Source: Dong Chinese Dictionary