An example of a grad-school level question?
When compared to current average conditions, which term would best describe conditions in Earth's lower atmosphere if greenhouse gases were absent?

An example of a grad-school level question?
The prairie grass ecosystem once had a deep layer of topsoil which was protected by the grasses that covered it. Removal of these grasses for farmland is causing the soil to be eroded mainly by

An example of a grad-school level question?
Sugar is added to water and the mixture is stirred. Which observation is evidence that the sugar dissolved in the water?

An example of a grad-school level question?
Which did Thomas Edison invent?