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

There once was a shoe factory.中,once 起什么作用? There once was a factory near sunshineriver There once was a factory near sunshine river There was once a steel factory in our city 怎么翻译?为什么不能用once 不 There was once a man once there was something wrong with a motor in a factory in 英语的两道改同义句There was once a factory near Sunshine River.______ there once was= 谁知道“Once there was a farmer .”全文 there was once a lonely girl 连词成句glad,was,took,and,once,them,to,a,shop,she,shoe,at once there was中文意思