Translation:We need to wash the apples for the salad.
Reported DL not accepting entity pronouns other than [ We ]
Any apple washing capable noun fits; girl, boy, children, relatives, friends, chefs, volunteers, someone, anyone, everyone, no one, the rain ...
Dative case - to need [ нужно ‧ надо ] The person or other entity which "needs" something is in the Dative: ‧ ‧ Надо is considered a bit more colloquial, though it is not very well supported by actual usage (for one, надо is not unheard of in academic papers ‧ нужно and надо are predicate adverbs, нужно can also be classified as a short predicate adjective or at least a word derived from one. A more modern description for such impersonal words is category of state. ‧ ‧ forum.duolingo.com/comment/12866931/Dative-case-to-need-нужно ‧ ‧ ‧ ‧ context.reverso.net/translation/russian-english/надо ‧
Мне надо ‧ I need to wash the apples for the salad
Тебе́ надо ‧ You need to wash the apples for the salad
Ей надо ‧ She needs to wash the apples for the salad
Ему́ надо ‧ He needs to wash the apples for the salad
Вам надо ‧ You need to wash the apples for the salad
Им надо ‧ THey need to wash the apples for the salad
Нам надо may be so common in Russian that leaving off нам isn't strange to a native-speaker.
My reaction was to mentally translate it as "one must/needs to" which in English is often expressed as a kind of general "we" - kind of like the Royal "We", except it's lower-case, and could be termed the common "we". It's a substitute for the more formal "one must".
It's also a substitute for "it", as in "it is necessary". I don't know why Duo doesn't accept "it is necessary", but Duo certainly should - unless my first thought is really strong in Russian - that a native-speaker naturally hears the unspoken нам. I tried it today, and it was rejected, so I reported it. The "correct" answer Duo gave me was "1 must wash the apples for the salad" - literally, the numeral "1", not the general pronoun "one".
It's really a shame that Duo leaves so much out which would help people understand the language at a basic level. I don't understand why the moderators do that. With a couple tweaks, Duo could be a stellar language program. As it is, it gets a solid C+/B-, less if they charged money.
I don't think it's a question of what the Russian means, so much as what a good English translation is for the sentence. It seems clear to me that the sentence addresses a general need for the apples to get washed. The question is, by whom?
In English, "one must/needs to/has to" and "we must/need to/have to" are "synonymous" (syntactically identical), while "I must/need to/have to" is definitely further removed in meaning, because it focuses on the single obligation. The generality of "one/we" is just not included in the specificity of "I". Another differentiation: "Someone has to" vs. "I have to". Two very different concepts of who has the obligation or need.
OTOH, "It is necessary" is pretty much the same as "one/we", because the unstated term in that construct is "It is necessary [for someone]..."
I don't think "I have to/need to/must" is a valid translation, because it's too specific. Similarly, I don't think it would be valid to say that надо could include "he/she/they" as possible subjects, again because it lacks the generality of "one/we", and leaving the subject off of надо speaks to a generality.
In some other context, those other pronouns might be implied/inferred, but not here (in English). But I'd be very surprised if they were accepted here, because it's not good English.
We need to wash the apples for salad - is rejected for leaving out 'the' in front of salad. Not an unusual inappropriate use of 'the', although it would be used if it referred to a salad previously identified. Like, "I am going to school", as distinct from "I am going to the school".