对国际原子时(TAI),地球力学时(TDT)和质心力学时(TDB)的定义和概念作了回顾和阐述。对其中一些有争议的问题进行了介绍和讨论。
This paper reviews the definition and conception of TAI , TDT and TDB , introduces and discusses some problems which are disputed recently among astronomers and physicists .