I thought Al meant "The"
I put The before the sentence and it's wrong. Why?
Is not اَلْأُسْتاذ The professor? Why then, "The professor Mohamed's room is weird." is not accepted? Someone else has asked the same question. See above, Please someone clarify this.
In English, you don't use "the" with titles followed by people's names. Just like you wouldn't say "I saw the Bob today," you don't say "I saw the Doctor Bob today."
"Mr. Muhammad's room" should definitely be accepted.