Complete the sentences (1-10) with the correct preposition. Use at, in or on. If a preposition is not necessary, put-.

1 at university

2 (-) next Monday

3 in five minutes (через 5 минут)

4 in the city centre

5 on time (вовремя; точно по расписанию)

6 At the back of the photo

7 In 50 years' time (Через 50 лет)

8 at their desks (за партами)

9 at the front of

10 on Saturday night (в субботу вечером)