Ответ:

15.3.

1... so we called the police  

2. I tried to phone Laura this morning, but there was no answer. She had gone out.

3. I met Jim a few days ago. Jim had just come back from holiday. He looked very well  

4. Yesterday Kevin got a phone call from Sally. He was very surprised.  He had sent her lots of emails,  but she had never replied to them  

15.1

2. It had changed a lot

3. She had arranged to do something else  

4. The film had already begun  

5. I  hadn't seen him for five years  

6. She had just had breakfast