Explain why the us is considered to be a republic and not a direct democracy

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 two advances did europeans borrowed from china

Who coined the phrase “go west and grow with the country”?