at. - О, в: The lesson begins at nine o'clock.
in - в, через: In summer we get up early in the morning.
on - в: School begins on the 1st of September.
from - с: Last year I stayed in the country from July to September, till (until) - до: Our lessons will continue till June, before - перед: Many new houses were built before the war. after - после: After the examinations we shall have our summer vacation.
by - за: Our classes are over by the end of May. during - до: Many children go to the country during their summer vacation.
for - за: In summer we rest for two months, between - между: Corne and see me between four and five.