YOU SAID:
once upon a time pigs might fly
INTO JAPANESE
かつては豚が飛ぶかもしれない
BACK INTO ENGLISH
Once a pig may fly
INTO JAPANESE
一度豚が飛ぶことができる
BACK INTO ENGLISH
Once a pig can fly
INTO JAPANESE
一度豚が飛ぶことができる
BACK INTO ENGLISH
Once a pig can fly
That didn't even make that much sense in English.