YOU SAID:
They sell weed and it's wonderful.
INTO JAPANESE
彼らは販売の雑草とは素晴らしい。
BACK INTO ENGLISH
They sell weed and is great.
INTO JAPANESE
彼らは雑草を販売し、素晴らしいです。
BACK INTO ENGLISH
They sell weed and is great.
That didn't even make that much sense in English.