YOU SAID:
If the light is off, then it isn't on
INTO JAPANESE
ライトが消灯している場合は点灯していません
BACK INTO ENGLISH
If the light is off, it is not on
INTO JAPANESE
ライトが消灯している場合、点灯していません
BACK INTO ENGLISH
If the light is off, it is not on
You've done this before, haven't you.