There once was a shoe factory.中,once 起什么作用?

There was once a man There once was a factory near sunshineriver there was once a lonely girl Once upon a time,there was a pretty ,fresh There was once a farmer who lived near a road. Once there was a man with a two-years-old 英语翻译开头是 Once there was a farmer.His. 英文短文,第一句：once there was a clever farmar 英文短文,第一句：once there was a clever Once upon a time,there was an emperor... Once Upon A Time There Was An Ocean 歌词 once,long ago,there was a man who travelled There was once a rich and kind store there was a time when能否写成 once there was a time when there once was=近义词 once there was中文意思 once there was no zero. There once was a shoe factory.中,once 起什么作用?