=Anno Domini [拉]公元【说明】A.D. 应该写在年数之前, B.C. 应该写在年数之后, 如: from 300 B.C. to A.D. 400 由公元前三百年到公元四百年
公元
1. in the Christian era; used before dates after the supposed year Christ was born; "in AD 200"
(synonym) ,