wash something down   
phrasal verb with wash verb uk/wɒʃ/ us/wɑːʃ/
  (CLEAN)      
  (用液体)清洗,冲刷(大件物品或表面)
to clean a large object or surface with a liquid
  He washed the car down with soapy water. 他用肥皂水清洗汽车。 
   (EAT)      
 informal(就着饮料)吃下,吞下 
to eat food or swallow medicine with a drink that helps or improves it
  Supper was fresh salmon and vegetables, washed down with a bottle of white wine. 晚餐有新鲜的三文鱼和蔬菜,就着一瓶白葡萄酒一起下肚。