High levels of ozone in the atmosphere can cause , which can trigger respiratory problems.

The meseta in spain is a a. navigable river b. castle c. coastal plain d.plateau

The us and canadian governments are doing all of the following to combat environmental problems except a. encouraging the use of public transportation b. enacting clean water policies c. requiring emissions testing d. limiting animal populations in some regions

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