previously

先前未知

describes something that was not known before the time of reference

以前不为人知。

以前闻所未闻

describes something that was not known or experienced before

以前不可能的

used for something that was considered not achievable in the past

用于过去被认为无法实现的事情

以前不可思议的

used for an idea or event so shocking it could not be imagined in the past

表示某事在过去是无法想象的。

refers to a person who was in a marriage before but is not now

以前未被注意到

indicates that something was not seen or observed before

表示某事在特定时间之前未被注意到。

indicates a prior status of being free from an obligation or liability

to refer to something that was spoken or written about on an earlier occasion

先前指出

to point out or observe something that was stated before

指出或评论先前陈述过的事情

to show or suggest something that was pointed out before

to have had possession of something in the past

to have been real or present in a place or situation in the past