YOU SAID:
Today is a lovely day isn't it?
INTO JAPANESE
今日は素敵な日じゃないですか。
BACK INTO ENGLISH
Today it's not a nice day.
INTO JAPANESE
今日の天気の良い日ではないです。
BACK INTO ENGLISH
Not good weather today.
INTO JAPANESE
今日の天気はよくないです。
BACK INTO ENGLISH
Today's weather is not good.
INTO JAPANESE
今日の天気はよくないです。
BACK INTO ENGLISH
Today's weather is not good.
That didn't even make that much sense in English.