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.
You can visit the US for up to six months a year (that means 182 days out of the past 12 months, not each calendar year). No visa necessaryâbut you must be able to prove you are a Canadian citizen or permanent resident and that you will return to Canada when your 182 days are over.And you must have a passport.anadians are allowed to visit the US for up to six months (182 days) per calendar year. Nationals of other countries are allowed only 90 days. You can accumulate those days by one long trip, or an aggregation of several short ones.