1.I was sitting on the bench for half an hour and then begun reading a book.
2. You saw him this morning? He was standing in the hall laughing.
3.He came on and saw Nelly who was drawing a strange picture.
4.I didn't understand what Mr Green was doing.
5.Nick and Fred were driving along the road.
6.-
7.flew
8. wasn't hear, said
9.was happening, happened
10.walked, was speaking
11. told, was eating
12.-, was watching
13. wasn't striking , stopped, was travelling
14.was sitting, came,said, was waiting.
15. didn't like,were working