at sea level, at the top of Mt. Everest, at a place in a valley below sea level, in an aeroplane flying at a height of 10,000 m with inside pressure maintained at the sea level" /> at sea level, at the top of Mt. Everest, at a place in a valley below sea level, in an aeroplane flying at a height of 10,000 m with inside pressure maintained at the sea level" /> at sea level, at the top of Mt. Everest, at a place in a valley below sea level, in an aeroplane flying at a height of 10,000 m with inside pressure maintained at the sea level" />