YOU SAID:

time flies by when you are having fun

INTO JAPANESE

楽しむとき、時間が飛ぶ

BACK INTO ENGLISH

Time flies when you have fun

INTO JAPANESE

楽しむとき、時間は飛ぶ

BACK INTO ENGLISH

When you have fun, time flies

INTO JAPANESE

楽しむとき、時間は飛ぶ

BACK INTO ENGLISH

When you have fun, time flies