Obviously in English, you can say stuff like "My German is terrible," or equivalent. But how is it in German? Is the following expression "correct"?
Mein Deutsch ist gut / schlecht / verbessert sich noch / usw.
(I realize that in this sense, the word "Deutsch" is synonymous with the word "Deutschkenntnis". So another way to phrase this question would be: can the word "Deutschkenntnis" be shortened to "Deutsch" in written as well as spoken German?)
"Deutsch" means German language. Deutschkenntnis means the knowledge of the German language and the ability to use it. It is usually used in plural (Deutschkenntnisse). So Deutsch is not a shortend version of Deutschkenntnisse and they are not generally synonym!
Two examples:
Ich lerne in der Schule Deutsch.
Ich habe gute Deutschkenntnisse.
In your sentence though, they can be used synonymly:
Mein Deutsch ist gut / schlecht / verbessert sich stetig / usw.
Meine Deutschkenntnisse sind gut / schlecht / verbessern sich noch / usw.
The sentence "Mein Deutsch ist gut" is perfectly fine, by the way, it is even listed as example in Duden:
"dein, euer, ihr, mein, sein Deutsch ist schlecht"
It's ok. but there belongs an "H" in "schlecht". But there is nothing wrong about "mein Deutsch". You can write it, too. EDIT: You've also messed up the letters in "Deutsch".
