"We are washing the tomatoes."
Translation:Wir waschen die Tomaten.
abwaschen is basically "do the dishes; do the washing up" and doesn't generally take an object.
(Though there's also abwaschen with the sense "to wash something (e.g. dirt) off from something else", e.g. den Schmutz [von den Tomaten] abwaschen. But here, the tomatoes are not being washed away from the surface of something else, so abwaschen isn't appropriate, in my opinion.)
It is a correct German sentence but not a correct translation of the English sentence.
The English sentence has "the tomatoes" (a specific group of tomatoes) and not "tomatoes" (tomatoes in general). The German translation should have die Tomaten and not just Tomaten.
In case you're wondering, I guess the reason that your (correct) explanation has received downvotes is that the method of asking Wen? Wem? Wer? and so on is completely useless to someone learning German as a second language. It works for German children because they instinctively know how to speak the language from experience, but just can't identify the grammar. It's the reverse process for most adult learners.
Hi az_p, as I understand the concept of duolingo is you learn a language by exercise not by learning the exact grammar notation. And yes, the question method is also used for children but not only. In my experience it is also very useful for adults. In every german lesson I had (not only as a child) it was a common way to identify the cases. It is also implemented in german courses for adults. So I don't think this method is useless for every adult.
To expect correct explanations of german grammer with a complete designation in a Internet platform like this is in my opinion a high requirement. If this kind of tip I gave is not wanted, of course I won't meddle in anymore.
Thank you for your answer, it helped me to understand what kind of help is desired. I'm only a short time active in this forum so I didn't knew.
best regards Angel
I've just seen it offered by well-meaning native-speakers several times, and yet never seen anyone whom it actually helped. The usual sequence is that someone doesn't know what wen means, so you try to explain accusative case (because new learners first assume everything is in nominative), which then requires explaining what an object is. Meanwhile you've got a couple of example sentences with dative verbs floating around confusing everything. The point being, nobody starting their exposure to German with Duolingo has any feeling whatsoever for Wer? Wen? Wem?. Duolingo's tips pages also teach case first and declension second.
It's similarly a struggle for me to explain English translations in the reverse language tree (English for German-speakers), because what makes sense to me as a native-speaker is unintuitive to a new learner. I'm often surprised by the tips that seem to resonate - they are usually things I never consciously thought about English before.