Why are fossils helpful in studying the prehistoric past

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

In the gettysburg address, which rhetorical device does abraham lincoln employ when he says, "the world will little note,nor remember what we say here, but ic never forget what they did here"?

What was the role of each class in aztec society?