at a time before the time that you are talking about (时间上)稍前的 The building had previously been used as a hotel. 这座楼房早先曾用作旅馆。 As previously reported, the couple separated in May. 如前所述,这对夫妇于5月分居。 The book contains a number of photographs not previously published. 这本书里有许多以前没有出版过的照片。 I had visited them three days previously. 三天前我曾探访过他们。 a previously unknown species 一个以前未知的物种