Should it help anyone: The nominative (and accusative) plural of Mitarbeiter being the same as the nominative singular is a pattern for masculine nouns ending in -er. My offline grammar guide (Schwarz Rot Gold, P. Webster) gives the guideline:
"masculine nouns ending in -el, -en, -er never add an ending in the plural, but some of them add Umlaut".
About feminine nouns it says:
"Most feminine nouns ending in -el or -er add -n for the plural"
It goes on to give two common exceptions, namely die Mutter and die Tochter which add umlauts but do not add -n.
Here is a similar guideline from an online source (so I can provide a link):
GUIDELINE: Nouns that end in 'el' or 'er' in the singular often do not change in the plural or only change their stem to an umlaut (see guideline above). Examples: der Löffel, der Vater, der Lehrer
The babelnation page doesn't mention about gender, but anyway "most nouns ending in the suffixes -er, -el" are masculine, with some notable exceptions: "die Trommel [drum], die Butter [butter], das Fenster [window], die Schwester [sister], die Mutter [mother], das Wetter [weather], das Zimmer [room] "
I believe nouns in this pattern always decline in the manner shown by the Mitarbeiter examples which both quis_lib_duo and mizinamo have already given on this page.
I have the feeling, when this sentence crops up as a multiple choice question, that it is testing recognition of this -er pattern.
I think that once more and more of the general patterns (of which there are many) become easier to recall, the exceptions to them begin to be the only things you have to remember. I think it's only overwhelming when you're trying to both recall the regularities and irregularities. This is by far the hardest stage, and it gets quickly easier I suspect. Also eventually the irregularities also become memorized.
I am right there with you polar.. I have decided that when I go to Germany to visit my relatives, they will thank their lucky stars when I attempt to speak with them in German, and will have to bear with any and all mistakes that I invariably shall make. One cannot expect perfection, just a general attempt. When someone non- native is speaking to me in broken english, I can usually piece it together anyway...
In nominative and accusative the form for sing. and plural looks the same, yes, so you need to pay attention to the article or other determiners. The declination is as follows:
nom. der Mitarbeiter
gen. des Mitarbeiters
dat. dem Mitarbeiter
acc. den Mitarbeiter
nom. die Mitarbeiter
gen. der Mitarbeiter
dat. den Mitarbeitern
acc. die Mitarbeiter
(If you speak about female coworkers exclusively, there are also the forms sing. die Mitarbeiterin, ... / plur. die Mitarbeiterinnen, ...)
So with mein, you would have
- mein Mitarbeiter
- meines Mitarbeiters
- meinem Mitarbeiter
- meinen Mitarbeiter
in the singular and
- meine Mitarbeiter
- meiner Mitarbeiter
- meinen Mitarbeitern
- meine Mitarbeiter
in the plural.
So the -e on meine Mitarbeiter is your only clue in this sentence that it's plural. (Well, and the verbal agreement.)
Why is "My felloworkers are great?" - (since Marx it is some kind of "tvarich" insinuation in Modern German?) Or simply grammar? - Wie sagst man "my fellow workers" im Deutsch, bitte? ("danken sie nicht - drei mark funfzig - sagt Louie zu mir? 109 pilot got shot down over France. Sehr Lustig.
I read all the explanations given here and I understand that it has the same form regardless if Sg or Plural , also I understand my mistake of writing " Meine Mitarbeitern sind toll " but why does Duolingo give back the response : " You used the plural "Mitarbeitern" here, instead of the singular "Mitarbeiter". " .
That totally gives you the wrong impression . It should say Mitarbeiter has the same form regardless if singular or plural . Das ist alles habe ich zu sagen und ich danke diese Seite dass sie uns hilft . Bis bald !
Mitarbeitern can only be plural (specifically, dative plural). That might be what's confusing Duo.
I think it doesn't do well in general with singulars that can look like plurals or nouns that can look like verbs -- it gets easily confused.
I don't think that can easily be fixed.
A human teacher would do better.