Gas exchange is the delivery of oxygen from the lungs to the bloodstream, and the elimination of carbon dioxide from the bloodstream to the lungs. It occurs in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli.
Admitted for 180 days â Canadians admitted in âVisitor for Pleasureâ or B-2 status without a B-2 visa in hand are deemed to be admitted for 180 days under current US Customs and Border Protection (CBP) interpretation of the rules.
Once you have lived in Canada as a permanent resident for a total of 4 years (1,460 days) during the past 6 years (including living in Canada at least 183 days during each of those four years), and after meeting other criteria, you may have the option to apply for Canadian citizenship.