More than a week ago, Thursday evening to be precise, Susanne was at her evening class.一个多星期以前，确切地说是周四晚上，苏珊在夜校上课。You have to be precise about the numbers.数字方面必须要准确。It's difficult to be precise about the number of deaths caused by smoking.死于吸烟的人数难以准确估算。