"I do not know her name."
Translation:Její jméno já neznám.
Proč ne Neznám jejího jméno? I think I should use the Accusative Singular form? Please let me know if I am wrong. Díky!
Jméno is neuter. In the Accusative Singular, the adjective endings and the word endings are the same in both the nominative and in the Accusative.
You would add -ho to the end if the noun was masculine.
Jejího bratra neznáme. = We don't know her brother.
Chápeš? Do you understand?
Ah ok. So the subject here was jméno and not she. Got it, thank you very much! :-)
No. The subject here is "I". The direct object, which takes the accusative case, is její jméno = her name. There is no "she" in the sentence.
It is more natural to use "vědět" for a subclause here:
I do not know, what here name is. Nevím, jak se jmenuje.
For a direct object "znát" is the natural verb to use.
In older, say 19th century, Czech the division was more fuzzy, but we do not consider it natural today.
Czech is not the only language to have this distinction, see https://www.livinglanguage.com/blog/2012/07/02/wissen-vs-kennen-to-know-in-german/
Grammatically there can't be a comma in "I don't know what her name is".
It would only work if you had a conjuctive adverb e.g. "Unfortunately, I don't know what her name is".
In Czech could you use "znát" for a subclause like " I don't know what her name is, she didn't tell me"? Or would you use "vědět"?
It is a separate relative clause ("what her name is") even if English doesn't use a comma to separate it graphically. Czech chooses to mark all subordinate sentences by commas.