The mathematical expression 9 & t means:
o9 union t
o 9 intersection t
9 is an element of t
9 is not an element of t

How do oceanographers measure the salinity of ocean water?

Why is the indus river so important to the people of pakistan?

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)