Questões de Concurso Para sefaz-ms

Se X, Y e Z são conjuntos, X ∩ (Y ∪ Z) = (X ∩ Y) ∪ Z: 

The main point in paragraph 4 is

According to lines 18 to 24,

Complete the following passage with the right prepositions in the right order:
Some 25 million surveillance cameras are already _____ place _____ stores and public spaces in the U.S. alone, and new ones are coming online _____ the rate of 2 million a year. _____ fact it's difficult to walk down the street without being photographed _____ several different angles.
(adapted from Next Frontiers in Newsweek, April3, 2006)

From paragraph 3 we infer that