Which practice is closely associated with most ancient river valley civilizations?

Which is an example of a country that is overly dependent on another country for goods and sevices

Ascientist performs an experiment where she measures the mass of a piece of metal, pours acid onto the metal, washes the metal, and then re-measures the mass of the metal. the scientist repeats the experiment several times, each time increasing the amount of acid used. the dependent variable in the experiment is the: initial mass of the metal final mass of the metal amount of acid used washing the metal

What was the significance of the battle of saratoga