Why are such phenomena as hurricane katrina and rare earthquakes in regions where oil shale is fracked called "hundred-year" events?

What does a movement along the demand curve show

Summarize the president's/vice president's roles and responsibilities in 8 sentences

Read the article titled "does the family farm really matter? " what reasons does this article suggest are the causes of the movement away from family farms to larger farms? (site 1 someone fast