在business里面unexpected occurrence是什么意思

在business里面unexpected occurrence是什么意思 none of one's business 可以用在作文中吗?雅思作文里面呢？ take their business是什么意思?在这句话里面：Once customers come to rely on these systems,they almost never take their business elsewhere 公益机构的nature of business我填的一个英文表格里面志愿者工作那一栏要填nature of business,在公益机构做志愿者,那么nature of business是填public interest吗? business business business business business Business Business business business business business business business business