one by one idiom
B2 逐个地，一个接一个
separately, one after the other
One by one the old buildings in the city have been demolished and replaced with new high rises. 这座城市里的旧楼一幢接一幢地被拆除，取而代之的是现代化的高楼大厦。
They entered the room one by one. 他们一个接一个走进房间。