I am sorry, wel and eens are two words but sometimes used togetter, I can recommend Dutch-learning students to use www.vertalen.nu you have a translater, you can use google translate, but on this site you can conjugate (vervoegen) and you have a sentence book (zinnenboek) type your words in and you get different sentences examples, I think it's very helpful, useful during your courses when one encounters some dificulties, I can give the link but it's possible you have to enter wel eens yourself : http://www.vertalen.nu/zinnenboek/?vertaal=wel+eens&van=nl&naar=en
I had got that. I just meant that in this exercise they are pronounced with a very long pause between them, as though there were a comma, which is not what one expects, if they constitute a set expression with a cumulative meaning. Thanx for the link, I had a look at the site and it looks really very useful!
I think there isn't much of a difference between wel eens and ooit. However, wel eens has a transparent etymology from words meaning well once, so it's inherently positive. On the other hand, ooit, while not actually a negative word per se, does not have a transparent etymology and tends to occur more in negative contexts (especially in the guise of nooit), similar to German jemals and French jamais. This slight difference in usage and connotations is similar to the one between sometimes and ever. So we roughly have:
- wel eens = sometimes
- ooit = ever
The two are often interchangeable in both languages, so it's not too surprising that often it's OK to translate wel eens by ever.
Ignoring the typo (if instead of of) under the assumption that you actually typed that correctly when answering Duolingo:
When you enter your translation, it is not individually assessed by a human or some extremely advanced artificial intelligence. There is a database of correct answers which is filled by humans. Depending on which platform you use to access Duolingo, you may have the option to request that your answer is added to the database.
But in general it's a good idea not to be too creative when answering and stick to very standard word orders.