A given volume of air contains only about one-third as much oxygen as it would at sea level.一定容积空气的含氧量只有海平面处空气含氧量的三分之一左右。Pay has been cut by one-third.薪水被削减了三分之一。The top one-third of all graduates are entitled to an education at the California State University.排名前三分之一的毕业生都获得了进入加利福尼亚州立大学学习的资格。