say how long they have been doing it
1)Mr.Robinson-since yesterday
2) Rose-since 2010
3)Frank-since Sunday
4)Willam and Sam-0.5 hour
5) Jenny and Alice-2.5 weeks
6)Molly and Kate-2.5 hours
7)Greg-0.5 hour
8)George-1.5 hours

Mr.Robinson has been doing it since yesterday. Rose has been doing it since 2010. Frank has been doing it since Sunday. Willam and Sam have been doing it 0.5 hour. Jenny and Alice have been doing it 2.5 weeks. Molly and Kate have been doing it 2.5 hours. Greg has been doing it 0.5 hour. George has been doing it 1.5 hours.