Use context clues about the nature of progressive taxes to come up with a definition of the word progressive.

Where is the vascular system located

Read the article titled "trans-saharan migration routes to north africa and the eu: historical roots and current trends." why do tens of thousands of sub-saharan africans try to cross the mediterranean each year? how are these refugees commonly portrayed? (site 1)

What first caused people to consider that the continents were once one large landmass?