1. While I was copying the exercise, my friends described a picture.
2. When we came in, the children were cleaning their desks.
3. We met her at the bus stop. She was waiting for the bus.
4. Some of the children went skiing, other children were skating. Everybody had a lot of fun.
5. When we came the family were getting everything ready for Christmas. Bob and Helen decorated the Christmas tree.
6. The girls fed the birds in the garden while the boys were making a bird-house.
7. When I came to my friend’s place, he was watching TV.
8. When I saw my friends, they were playing football.
9. When I opened the door, the cat was sitting on the table.
10. When Kate opened the door, the children were dancing round the fir-tree.
11. When Tom was crossing the street, he fell.
12. When I was going to school, I met my friend.
13. When we were going to the cinema, we met grandmother.
Объяснение:
2-needn't buy
3-mustn't go
4-needn't give
5-mustn't shout
6-mustn't miss
7-needn't go