Which type of economic activity has grown more important in modern economies in recent years? quaternary secondary primary tertiary

Most countries in the middle east must import a majority of their a. gasoline b. oil c. food d. water

Some gamma ray bursts are hypothesized to come from mergers of neutron stars or black holes. if this hypothesis is correct, what else should we in principle be able to detect from such mergers? a. gravitiational waves b. x-ray bursts c. significant disruption of gas thousands of light-years away in the surrounding galaxy d. an "afterglow" of bright visible light, lasting for weeks

Which of the following best describes the circumstance under which countries block the importation of certain products into their country? a. importation blockade b. trade barrier c. trade inhibitor d. domestic protection act