Earth is very old, and it can be difficult to visualize where key events in the history of life occurred against this backdrop of "deep time." one common way to represent geologic time uses the analogy of a one-hour countdown timer. the timer starts from the top at earth's origin (4.6 billion years ago) and moves clockwise to the present, making one full circle. in this analogy, one hour represents 4.6 billion years, one minute represents roughly 76.67 million years, and one second represents roughly 1.28 million years. (open hint 1 for an explanation of how these calculations are done.)

1.0 billion years old
2.0 billion years old
2.3 billion years old
4.5 billion years old

One day as your professor is driving to work, another driver runs through a red light and hits his car. the professor is shaken up but survives the accident. however, the next time he starts to enter the intersection,he becomes nervous and fearful. soon,he starts going to work via another route to avoid the intersection even though this route adds twenty minutes to his commute in each direction. according to the principles of classical conditioning, why does the professor become scared of the previously harmless intersection? what can he do about this, as going via other route is very time consuming? be specific. break down the situation into its parts and show how the principles of learning apply.

6. why did louis xvi call a meeting of the estates-general in 1789? how long had it been since such a meeting had been called?

What would be considered a secondary source about the assasination of abraham lincoln