1) They were at the university in the morning.
Were they at the university in the morning?
When were they at the university?
Where were thet in the morning?
They were at the university in the morning, werent' they?
Were they at the university in the morning or in the afternoon?
2) It is the best day in my life.
It is the best day in my life, isn't it?
Is it the best day or the worst day in your life?
Is it the best day in your life?
What day is this day for you?
3) He will be at home at 6 o'clock
When will he be at home
Where will he be at 6 o'clock?
He will be at home at 6 o'clock, won't he?
Will he be at home or at the university at 6 o'clock?
Will he be at home at 6 o'clock?