"Ich muss meine Mittagessen kochen."
I don't think that it is never said like this, mostly you never use plural of lunch, and for sure not in this example..
As I know Mittagessen is not used in plural in Germany. The same I assume for English. However it is gramatically correct.
what a bizarre phrase - why can't Duolingo give us useful phrases. Or are they deliberately trying to trip us up.
Apparently because it's "meine Mittagessen" and not "mein Mittagessen". That being said, "I must cook my lunches" sounds like something nobody would every say.
Neither 'meine Mittagessen'. It's just an odd example. How many lunches can a person possibly need? That being said, you might precook your food for the next days, as it used to happen in my family, then they said: Ich muss das Mittagessen der nächsten Tage [of the next/following days] vorkochen.
Lunches can be used in odd cases. Generally it is singular. I imagine because "lunches" sounds terrible, people tend to re-word the sentence like in your example: "I made myself lunch for the next couple of days". Here's an example of lunches:
- "Chef, I made all the bagged lunches for the kids' field trip."
- "How many did you make?"
- "What about the gluten-free lunches?"
- "What do you mean Chef?"
- "I needed 2 gluten-free lunches. 28 regular, and 2 gluten-free."
- "Sorry Chef, I didn't know. I'll get right on that Chef."
- "Stop wasting my time and money Sheffield. You stupid donkey."