I don't think "always bought" seems okay, and even if it is in English, then it translates to "zawsze kupiłem" which doesn't really make sense in Polish.
"I always bought eleven lemons" is a perfectly good English sentence, but I think it would primarily be used in a context where you're saying when you always bought the lemons. As in: "I used to go to that store over there, and whenever I did, I always bought eleven lemons."
All that said, I feel much better translating "zawsze kupowałem" as "I always used to buy" than as "I always bought".
i wrote "i bought always eleven lemon" .could it be a good answer .I se that the answer of duolingo is very complicated .Thanks for your comments
"I bought always eleven lemon" is definitely not a correct English sentence.
"Always" should go before "bought", and it needs to be "lemons" instead of "lemon".
I always was buying eleven lemons. This is correct English, does it translate correctly with Polish. It would emphasize the 'always'. It was marked wrong with the correction putting the was before always (which is also correct in English).