4 sentences

1. 鹅卵石被水流冲刷得十分圆滑。

   é​luǎn​shí bèi shuǐ​liú chōng​shuā de shí​fēn yuán​huá.

   The pebbles have been worn smooth by the flow of water.

   Source: Dong Chinese Dictionary

2. 海浪的不断冲刷侵蚀了岸边的岩石。

   hǎi​làng de bù​duàn chōng​shuā qīn​shí le àn biān de yán​shí.

   The constant washing of the waves has eroded the rocks along the shore.

   Source: Dong Chinese Dictionary

3. 由于长期的水流冲刷，地面形成了一道深壑。

   yóu​yú cháng​qī de shuǐ​liú chōng​shuā, dì​miàn xíng​chéng le yī dào shēn hè.

   Due to long-term water erosion, a deep ravine formed on the ground.

   Source: Dong Chinese Dictionary

4. 海边的这些岩石在海水的冲刷下变得很光滑。

   hǎi​biān de zhè​xiē yán​shí zài hǎi​shuǐ de chōng​shuā xià biàn de hěn guāng​huá.

   These rocks by the seaside have become very smooth from being washed by the seawater.

   Source: Dong Chinese Dictionary