3 sentences

1. 他弯下腰去系鞋带。

   tā wān xià yāo qù jì xié​dài.

   He bent down to tie his shoelaces.

   Source: Dong Chinese Dictionary

2. 他弯下腰，捡起落在地上的钥匙。

   tā wān​xià yāo, jiǎn​qǐ luò zài dì​shang de yào​shi.

   He bent down and picked up the keys that had fallen on the ground.

   Source: Dong Chinese Dictionary

3. 他忍不住弯下腰，从锁孔向屋内一窥。

   tā rěn bù zhù wān​xià yāo, cóng suǒ​kǒng xiàng wū​nèi yī kuī.

   He couldn't help bending down to peek into the room through the keyhole.

   Source: Dong Chinese Dictionary