Prepositions of time:
In / at/ on/ from........to
I. “on”: is used with:
a. Days of the week: on Friday/ on Monday/ on Saturday……
b. Date : on 15 th April/ on 23 rd December/ on the 15 th of April…
c. A special part of a day : on Friday evening/ on Monday morning…
II. “ at”: is used with:
a. Part of the day: at night/ at noon…
b. Time of day: at 7:00/ at 9:00/ at midday/ at midnight/ at sunset/ at sunrise…….
c. Celebrations: at Christmas/ at Ester……
d. Fixed phrases : at the same time/ at present/ at the moment…………
III. “in” is used with:
a. Months: in July/ in May/ in December…
b. Year: in 2012/ in 1999/ in 1985/ in 1970 s …
c. Seasons: in summer/ in spring/ in autumn/ in winter…
d. Part of the day: in the morning/ in the evening/ in the afternoon……………….
e. Duration: in weeks time/ in a minute/ in two weeks……………………………………
IV. “from…….to……” :
'From......TO' is used with limited periods of time:
From seven o’clock to nine o’clock
from Monday to Saturday 
