His only connection to the outside world was an air tube and a bell. Each day he rang a bell to let those outside know that he was still alive.
墓内的僧人和外界的一切联系只有一根输气管和一个铃铛，每天僧人都会摇铃使外面人知其还活着。
2
While concentrations varied daily, typical concentrations of lead particles ranged from 0.6 to 1 microgram per cubic meter of air, Bell and her thesis adviser Catherine Cahill found.
Because it needs air to work, we won't be using it to move spaceships any time soon, but Alexander Graham Bell didn't have "call waiting" or "text messaging."