"Die Lehrer trinken Milch."

Translation: The teachers drink milk.

[retsecabret]

Why lehrer can be : teacher and teachers?

[insomniaxy]

sometimes you can see if it is singular or plural only by article or adjective in front of the noun or by following verb.. you have to know particular noun.
in this case. singular is "der Lehrer trinkt" and plural is "die Lehrer trinken"

[agm05]

Thank you!

[QHjr]

Thanks!

[Avijan15]

also when it says Die in front of Lehrer you know its plural

[Jonathan-Conrad]

In front of Lehrer, yes, but that is not always true.
Such as Die Mutter (the mother) in plural is Die Mütter.
Have to be careful

[amorimleandro]

But in this case you have to note the verb, which is conjugate for plural.

[Jotamide]

Why is "professors" incorrect?

[AgenTsi]

"Professors" in german is "Professoren." It's a different word.

[eplus17]

Not all teachers are professors (and not all professors, at least in the US, have teaching as part of their responsibilities;) "teacher" and "professor" are two distinctly different concepts.

[KemonRamon]

What is different about Lehrer & Lehrerin?

[Occams_Razor]

I think the former is a male teacher and the latter a female

[machobo]

Yeah you're right! The ending "-in" for an occupation etc. is a typical female ending: Lehrer / Lehrerin (teacher), Arzt / Ärztin (doctor), Bauer / Bäuerin (farmer), Spieler / Spielerin (gamer) and so on