An example of a grad-school level question?
Which of the following is the main role of flowers found on most flowering plants?

An example of a grad-school level question?
Which structure surrounds and protects an animal cell?

An example of a grad-school level question?
Clouds and precipitation moved across western Massachusetts one evening. The temperature changed from 41F to 28F. Which of the following changes in precipitation most likely occurred on this evening?

An example of a grad-school level question?
Which of the following helps keep the Moon in its orbit?