Which water source becomes polluted as it travels over the earth? ponds groundwater oceans runoff

Below is a description of a resource that you're considering using for a research paper. as you read the description, keep in mind what you've learned about historical thinking skills and use those skills in evaluating whether or not to use the source.

Many members of the civilized tribes farmed

Martha participates in a research study in order to receive extra credit for her psychology class. when she arrives in the research office she is given a can of what looks and tastes like beer, but which actually contains no alcohol. in the adjoining room martha's classmate karen is also participating in the study. karen receives a can of alcoholic beer. if the experiment was designed to test the effects of alcohol on concentration, then who is exposed to the independent variable?