肺细胞约每周新老更替一次。Lung cells die and are replaced about once a week.昼夜更替.Day and night alternate.从事高等教育的人员新老更替极其缓慢。There has been very little renewal of personnel in higher education....
联邦制意味着存在众多各自都拥有权力的政治管理机构。Federalism implies a plurality of political authorities, each with its own powers.权力的争斗近期不会终止。There is no end in sight to the struggle for power.副总统现在必须承担起最高权力的重任。The vice-president must now take...