Interested in Language
Is it correct just to use can when you speak about a language?
Can you English?
I hope you can this language.
Usually I would say:
Can you write English?
Can you speak English?
Can you read English?
Would just can be enough?
Does it contain everything (writing, speaking, reading etc.)?
(It would not be illogical in my opinion, but logics and language do not always matter.)
As you know (can, must etc) are auxiliary verb. They help sentence to be meaningfull. That's why it is impossible without verb. You use "can" without verb when you answer or response something. We know that "CAN" sometimes imply : ability, permission or possibility. So it needs verb.
"Ich kann Englisch" - I can speak English / I know English.
(Edit: sorry, I have just noticed that the original poster is German :/)
Incidentally you can also have sentences like these in English:
"I can't speak German but I can English."
"I can't speak German as well as I can English."
- but here of course the verb "speak" is understood again in the second part of the sentence.