I know this question is super old, but... why is Die Frau isst Apfel grammatically incorrect?
The direct translation into English, "The woman eats apple" is grammatically correct (but subtly different to the translation exercise here) because most foods in English can be used as mass nouns.
Saying "...eats apple" just says that she sometimes eats some amount of apple(s). Not specifying that she eats one, or more than one, or half of one, or these ones or those ones... just some amount (which does not have to be a whole number).
Is the "food as mass noun" thing from English not done in German? Are foods typically referred to as plural in this situation? Would I have to ask Isst du Wassermelonen? (literally, "Do you eat watermelons?"), even though it's ridiculous for someone to eat multiple of them? I thought that some foods were treated as mass nouns, like Isst du Fleisch und Brot?.
English and German have not the same grammar. Im from German, my english isn't good - sorry for this, I'm just learning - but I can say, if I do or have anything with a thing (noun), I need a articel. "Ich habe einen Apfel" oder "Ich habe den Apfel", "Du hast ein Buch" oder "Du hast das Buch", "Er hat eine blaue Hose an / Er trägt eine blaue Hose" oder "Er hat die blaue Hose an / Er trägt die blaue Hose". I cannot eyplain why, but "Er hat Apfel" sounds not good (klingt scheiße!) and stupid in the ears of german people. But "Er hat Äpfel" sounds good and is correctly. Has he any apples, we say "Er hat Äpfel" oder "Er hat ein paar Äpfel", but has he few specified apples, then we say: "Er hat die Äpfel".
A note to the Team: "Frau" sounds not correctly. It sounds like "Fra". There is missing the "u" in articulation.
I'm German and I agree that "Sie isst Apfel" is not grammatically wrong. It sounds very strange though and nobody would use it in spoken or written language. If you want to say that she generally/usually eats apples, as in "Sie isst Fisch", you'd rather use the plural: "Sie isst Äpfel". Even though in fact she might have eaten only one apple in her life (maybe if you're talking about a very young girl that has just eaten her first apple ever). It's kind of weird and I can't really tell why you'd use the singular with Fisch and the plural with Apfel, but that's what it's like from my point of view.
"The woman eats apple" in English is NOT grammatically correct. It would either be "The woman eats apples" or "The woman eats an apple" or "The woman eats the apple". Apple is not considered a mass noun, it is able to be counted. Mass nouns are words like water, bread, wood, etc. where they need further explanation to count. You can imagine what 1 apple or 7 apples look like, but what is 1 wood? Or 5 waters? You can't count wood, or water, unless you say one liter of water, or one plank of wood, or something similar, but then you are no longer counting wood or water, you are counting liters or planks.
Have you tried changing the language input of your keyboard or typing Ae for Ä? I don't have an ä key on my keyboard either but I was able to change my Windows system's Region and Languages setting to make my keyboard type umlauts. I haven't tried submitting ae for ä on Duolingo but substituting e for umlaut is an acceptable way to write Ä/Ae, Ö/Oe and Ü/Ue in many parts of the world.
For what it's worth, I tried "Die Frau isst Aepfel" and it replied "Almost correct! Die Frau isst Äpfel." It does accept Xe for other phrases; I haven't cracked the pattern (or definitively determined that its list of acceptable alternatives is less complete in some areas) yet.
Frau = Woman, not wife.
Also, in German, I don't believe there is a conjugation/slang for "eat" to make it plural like we would in English. We might write "The woman eats apples", whereas in German it would be "The woman is eating apples". Even in English, I don't believe "The woman eats apples" is correct as it would be more proper to write "The woman is eating apples" instead. "Is eating" always takes the place of the use of the word "eats" in English sentences (Unless you want to vary the meaning slightly) so I can only assume it's an English-specific thing.
The woman eats apples is perfectly correct. It means an adult female human being consumes as nourishment apples which are a specific kind of fruit. She is eating apples is actually a weirder sentence as it kinda implies, without further context, she is eating more than one apple at once! English modifies its tenses with aspects. 'She eats an apple' is just the present tense with no aspect, often called the simple present tense. 'She ate an apple' is the same sentence in the simple past tense. 'She is eating an apple' is not the same sentence as 'she eats an apple' and has subtly different grammatical meaning. It's more obvious with plurals in this context but the former means a female is currently in the process of eating an apple. The latter does not mean this, though it does imply it. This is the present tense modified with the continuous aspect which indicates the verb is still ongoing or alternatively has not been completed.
Consider 'she eats an apple daily' to get the difference. Here I am informing you of someone's habit to eat an apple daily not that she is currently eating her daily apple. 'She is eating an apple' is the present tense continuous aspect.
English then has 4 tenses each modified by 4 aspects. The tenses are: present, past, future and future past. The aspects are: simple, continuous, perfect and continuous perfect. Together they combine as follows for the verb 'to go':
The simple present - I go
The simple past - I went
The simple future - I will go
The simple future past (or future-in-past) - I would go
N.B: the last one is trickier but normally you only have to worry about it for conditionals.
The continuous present - I am going
The continuous past - I was going
The continuous future - I will be going
The continuous future past - I would be going
The perfect present - I have gone
The perfect past (also known as the pluperfect)- I had gone
The perfect future- I will have gone
The perfect future past - I would have gone
The perfect continuous present - I have been going
The perfect continuous past - I had been going
The perfect continuous future - I will have been going
The perfect continuous future past - I would have been going
To think we English complain about the verbs of other languages! There are a few other odditites floating about I think but some are just old names for things such as the pluperfect for the perfect past.
It might be a bug in Duolingo. That said, usually the alternative spelling is only acceptable when it's not possible to input special characters - and Duolingo does allow you to input them. If the on-screen special character buttons aren't there, or you can't get them by long-pressing on a touchscreen keyboard, see here.
Perhaps you made another mistake unintentionally. The correct answer is "The woman eats apples".
A lot of people who already speak English end up learning more about their own language in the process of learning another one. Duolingo here highlights the difference between "woman" (Frau) and "lady" (Dame).
Both "eats" and "is eating" are possible translations, without context (as is the case with most sentences on Duolingo).
Without the context of a conversation, you could only tell the difference if the sentence itself provides context such as "(she is eating apples) right now" or "(she eats apples) every day".
My reply to this sentence was “the woman is eating the apples“ and it came out as a wrong answer.
Äpfel is "apples", not "the apples".
die Frau isst Äpfel = the woman is eating apples
Writing "...is eating the apples" is not a correct translation of ...isst Äpfel.
Lingot to you for quoting your entire sentence rather than simply assuming the problem was with the verb form and complaining that "is eating" is not accepted.