Dear Teacher...
I put a wrong question a few minutes ago.
The right question is : "This problem is answered by nobody'"
The above sentence is wrong?
If so, I'd like to know the reason...
Best regards...
I didn't see the original or the context, but this one looks fine to me, Nautes. I might have written 'has been answered', but your grammar is correct out of context.
You mean "The problem was solved by nobody."is correct?
Yes. What do you suppose is wrong with it?