1 .......had been watching the building for an hour.......
2 .........had been studying it since 2001
3 ........had been working since 5 a.m.......
4 We had been living here since 2007.......
5 The telephone had been ringing for five minutes...........
6 .......had been feeling unwell for two weeks..........
7 Lucy had e playing the piano since she was a child.