Use the verbs in brackets in Past Perfect:
1. He asked me if I … (have) breakfast.
2. He was pleased to meet Dave again. He … (know) him for ten or eleven years, and they … (play) together in London many times.
3. She realized that she … (do) nothing since the contest
4. He did not know what … (happen).
1) had had a breakfast
2) had known
3)had played
4)had done
4)had happened