"Nous sommes en train d'acheter des fruits."
Translation:We are buying fruit.
"être en train de + infinitive" means "to be in the process of, in the middle of". It expresses something that is happening right now. Like
Je suis en train de dîner → I am (in the middle of) having dinner.
In this sentence it means "We are (in the process of) buying fruit."
I suppose that is why this is verb plus infinitive versus conditional, which is a simpler way of saying during or in the middle of, though more difficult to learn. I think your comment is very helpful.
But "we are in the process of buying fruit" was rejected. I know it's awkward but a lot of Duo's translations are awkward. Will report.
...in the process of... must be right here - at least as an option. You need to express the immediacy of the action, and "We are buying fruit" does not do that unambiguously. Nous achetons des fruits could also be translated as "We are buying fruit" but it does not mean the same thing.
This is getting crazy. I was still typing and I was marked incorrect. Yet there is no way to report this to Duolingo.
I wrote 'we are in the process of buying fruits' and it was marked wrong. What is the point of using 'en train' then??
we are buying fruits did not make it, and it is not idiomatic, but it it grammatical and not a semantic violation. But my question is, is there a fruit/fruits issue in French as well, since des fruits is plural, no? My Practique Larousse give fruit as masculine, so what would I be saying in French if I used du fruit?
des is the plural of un / une.
un fruit is a single piece of fruit. des fruits is fruit plural. In English we use the word fruit as a plural and, to singularise it, we either say "a piece of fruit" or, for example, "a tomato is a fruit".
I would say, if it were a single piece of fruit being purchased, then the French sentence would be Nous sommes entrain d'acheter un fruit.
I don't know if that helps at all. :-)