(Prepositions (part 1

at: a time ( exp: at six o'clock, at midday) / 

      a mealtime ( exp: at breakfast) 

on: a day (exp: on friday, on my birthday) / 

       a date (exp: on september, on the sixth of May) 

In: a part of a day (exp: in the morning) /

      a season (exp: in the spring) /

      a month, year or century (exp: in July, in 1990)