c временем, например:
at - at 5 o'clock, at half past one, at night
in - in the morning, in 1998, in summer, in November
on - on Monday, on the 4th of September
предлоги места:
at - at the table (за столом), at the blackboard(у доски)
in - in Moscow, in the park, in the box в...
on- on the table, на...
есть ещё много случаев употребления. Эти - основные.