An example of a grad-school level question?
The Sun appears to move across the sky each day, rising in the east and setting in the west. What causes this apparent motion?

An example of a grad-school level question?
Oil, coal, and natural gas are fossil fuels formed under what conditions?

An example of a grad-school level question?
When the pesticide DDT was first used, it killed nearly every mosquito it touched. Within a few years, however, many mosquitoes became resistant to DDT and survived. What enabled this to happen?

An example of a grad-school level question?
Scientists think that dolphins and whales may have evolved from a common ancestor. What evidence supports this hypothesis?