Fill in the gap with prepositions of time: Are you going on holiday ... the summer?

Fill in the gap with prepositions of time: in, on, at, beetwen, before/ after
1. Are you going on holiday ............... the summer?
2. They will leave .............. 7 o'clock
3. The museum is open ............ 7 a.m ............. 5.p.m
4. We must be at home .................6 p.m
5. The World Cup often starts ............... June 10th after every 4 years
6. l'll see you ............. lunchtime
7. They don't go to school ............. Sunday