Помогите пожалуйста

Underline the correct preposition.
1 They met on / at / in 11 June.
2 Kate was born in / at / on the 1980s.
3 We play tennis on / in / at weekends.
4 She bought the flat at / on / in May.
5 What did you do in / at / on Monday?
6 I usually have breakfast in / at / on 7.30.
7 I was born on / in / at 1990.
8 Did you see Mark on / in / at Saturday evening?​