YOU SAID:
Tomatoes are red, potatoes are blue, why did I say potatoes are blue?
INTO JAPANESE
トマトは赤く、じゃがいもは青い、どうしてじゃがいもは青いと言った?
BACK INTO ENGLISH
Tomatoes are red, potatoes are blue, why did you say potatoes are blue?
INTO JAPANESE
トマトは赤、じゃがいもは青い、なぜじゃがいもは青いと言ったのですか?
BACK INTO ENGLISH
Tomatoes are red, potatoes are blue, why did you say potatoes are blue?
That didn't even make that much sense in English.