mưa như trút nước 
it’s raining cats and dogs [ mưa ] : to rain; rainy
[ như ] : like, for example, as, such as, similar
[ trút ] : to unload, pour, dump
[ nước ] : country, nation, state; water, liquid (for drinking); gum(s) (flesh surrounding teeth)
Most Common Compounds Set 1:
Most Common Compounds Set 2 :