Moreover, in the odd case of multiple sons named "Peter", "name" would also be pluralized. I.e. "My sons' names are Peter." So the verb would be plural हैं and the singular oblique बेटे would be replaced by the plural form बेटों. So, George Foreman might say
मेरे बेटों के नाम जॉर्ज हैं
Mind you, take that with a grain of salt. Someone who actually already knows the language may end up correcting me. :-)
I have boiled it down to this. Oblique case is what happens to the words in front of the postposition. When using 'ke', something must happen to mera beta. If not it will sound wrong. So whenever there is a postposition there will be an oblique case. I am still learning. Correct me if I'm wrong.
It's never wrong to use the honorific plural. But when Duolingo is expecting singular, it usually doesn't accept plural.
Note that the statement you gave has two errors.
- I think you mean बेटे, not बेते.
- But if you use a plural verb, you also have to pluralize "son". And because of का नाम it needs to be oblique. So you'd need to use the oblique plural बेटों.
"direct" and "oblique" are references to different cases. These are covered in the tips to a couple of the early skills. I forget which.
"plural" and "singular" refer to how many.
Also see the reply I just posted to Sunnymonie's question, "So how do I know if we're talking about my son or sons?"
I found this confusing too. I feel your pain. :-)
I'll start with examples:
- मेरा बेटा - My son
- मेरे बेटे - My sons
- मेरे बेटे का दोस्त - My son's friend
- मेरे बेटों का दोस्त - My sons' friend
What makes it hard is that there are four ways to inflect बेटा, but two of them happen to be the same. So there are only three different words.
- बेटा - This is the direct singular. E.g. "son" without any postposition.
- बेटे - This could be direct plural. E.g. "sons" without any postpostion.
- बेटे - This could also be oblique singular. E.g. "son" with a postposition.
- बेटों - This is oblique plural. E.g. "sons" with a postposition.
If there's no postposition, बेटे has to be direct plural.
If there is a postposition, बेटे has to be oblique singular.
Caveat: above is oversimplified. There are multiple things to watch out for. The big two are:
- Honorific plural.
- Implied postpositions (a.k.a. "ghostpositions")