YOU SAID:
There once was a sailor
INTO JAPANESE
かつて船乗りがいました
BACK INTO ENGLISH
Once there was a sailor
INTO JAPANESE
船乗りがいたら
BACK INTO ENGLISH
If there is a sailor
INTO JAPANESE
船乗りがいる場合
BACK INTO ENGLISH
If there is a sailor
You've done this before, haven't you.