bottom,ground.land.floor 区别

bottom: 1.the lowest part of sth 底部,最下部
2.the lowest surface on the insude of a container（容器内的）底
3.the ground below the water in a lake, river, swimming...（湖,河,游泳池等的）底,水底
4.the part of sth that is furthest from you, you house......的尽头
eg. there is a stream at the bottom of the garden花园的尽头有一条小溪

ground: 1. the soild surface of the earth地面；地通常用作the ground
2.soil on the surface of the earth 土；土地；土壤
3.an area of land that is used for a particular purpose, activity or sport（特定用途的）场地
4.an area of interest, knowledge or ideas（兴趣,知识,思想的）范围,领域
ground常指室外, 地面

land: 1.the surface of the earth that is not sea陆地
2.(涉及感情或想象）国家,地区 motherland祖国
land 强调海陆的对比

floor: 1.the surface of a room that you walk on室内的地板,地面
2. the bottom surface of a vehicle（车厢内的）底板

仔细观察你会发现这些词的侧重点死不一样的,查字典时一定要看英文解释和例句,因为有些时候中文是比较不出来的