B2 [ C ] the bottom part of an object, on which it rests, or the lowest part of something基底，底座；底层，底子

B2 [ C ] the main place where a person lives and works, or a place that a company does business from基地；总部

a place where there are military buildings and weapons and where members of the armed forces live军事基地

[ C ] one of the four positions on a square that a player must reach to score a point in the game of baseball（棒球运动中的）垒

[ C ] the activity or people from which someone or something gets most of their support, money, etc.基础，支柱

C2 [ C usually singular ] the main part of something主要成分

[ C usually singular ] specialized mathematics the number on which a counting system is built基数

[ C ] specialized chemistry a chemical that dissolves in water and combines with an acid to create a salt碱，盐基

not showing any honour and having no morals贱的；卑下的，卑鄙的

B2 to have a particular town or area, etc. as the main place that you live and work in, or where you do business from以某处（城市或地区等）作为生活、工作、经商的主要地点；将某地设为总部