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.
People mentioned above are required to obtain a visa prior to arrival if they decide to stay in Canada for more than 6 months. According to Citizenship and Immigration Canada, people from countries whose citizens do not require a visa to visit Canada (including the US), are allowed to stay in the country for up to a maximum of 6 months per year. However, the immigration officials at the point of entry decide for how long you actually are allowed to stay.