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IN and On are prepositions . They have many uses.
There are three apples in the box on the table.
IN a year . For example in 1991
In a month.For example in july.
IN a week .For exaple in a week
On a day .For example on monday
At : When you're specifying an exact hour or to make an appointment
I woke up today at nine o'clock.
We'll meet at seven-fifteen It's not used before "Time", we use "what" instead : Whattime will you be ready? We also say : At christmas - At weekends - At the weekend - At easter...
On : Always used before days of the week and specified days : She died on Monday
He'll travel on April 7th
In : Always used before months, years, centuries... In July In 1986 In The 21th century
Talking about space, you use :
At : When there's no moving (to be, to stay,ect...) unlike "to" (when there is a moving)
He's At school
He's going to The high school
On : When you're marking the top of the fellowed noun (object, place...)
Put that On my desk
They lie On the floor
In : finally when you mean the inside of the fellowed noun
throw it in that rubbishbin
I'm hidding stuff in my pocket
in or on? 
Re: in or on? 
Linear Mode
