Ya why do we say This fan blow very hard and not This fan blows very hard..i am confused with this differnce .
Also in the sencond sentence the person to whom i want to ask the question doesn't studies accounts any more he has completed his studies few yeras before so am i still suppose to" How were you at accounts."
We don't say "This fan
blow very hard" - who told you that we do?! "This fan" is 3rd person singular and takes "
blows"
If the person in the second question no longer studies accounting, then you can say "How were you at accounts/accountancy/accounting (depending on the name of the actual course)?" Of course, this would only work if you were already talking about the time when he was a student. If you made this the first line of a conversation, I don't think it would necessarily be understood, and you would need to say something like "When you were a student, were you any good at accounting?"