1、作副词
①大约,左右.如：There are about 30 students on the playground.操场上大约有30个学生.
②将要,将近.如：I’m about ready.我快准备好了.
③到处,各处.如：The children are running about.孩子们到处乱跑.(表示动向)People are sitting about on the grass.人们在草地的各处坐着.(强调位置)
2、作介词
①在……到处；在……各处.如：He is walking about the town.他在城镇到处走.
②关于；对于；有关.如：I am going to read a book about that big city.我要读一本关于那个大城市的书.
3、固定搭配
①be about to do sth.如：We are about to start.我们即将动身.
②what/how about...……怎么样?(用于询问信息或征求意见)如：How about going to Canada for our holidays?咱们去加拿大度假,好吗?