Prepositions for Time

1. on > Days of the week. eg: on Saturday
2. in > months/seasons/ time of day/ year/ a certain period of time. eg: in December. in winter. in the afternoon. in 2011. in two hour.
3. at > for night/ for weekend/ a certain point of time. eg: at night. at the weekend. at half past time.
4. since > from a certain point of time till now. eg: since 2004.
5. for > over a certain period of time till now. eg: for 5 years.
6. ago > a certain time in the past. eg: 3 years ago.
7. before > earlier than a certain point of time. eg: before 2010.
8. to > telling the time. eg: fifteen to one. (12:45)
9. past > telling the time. eg: half past one. (1:30)
10. to/ till/ untill > marking the beginning and end of a period of time. eg: from Friday to/till Sunday.
11. by > in the sense of at the latest up to a certain time. eg: I will be back by 10pm tonight.