4 in / at / on Complete the time expressions with in, at or on.

4. Time expressions with in, at, or on

1. on Saturday
2. in summer
3. in the twenty-first century
4. at eight o'clock
5. on the 12th of March
6. in June
7. on Monday morning
8. in 2010
9. on my birthday
10. in the 1980s
11. at the weekend
12. in the afternoon