1) I/surf the Net 2) Mike/have lunch 3) Daniel/already get to airport…

1-c) I was surfing the Net when we suddenly had a power cut. 2-d) Mike had lunch and then did the washing-up. 3-a) Daniel had already got to the airport when he realised he had left his passport at home. 4-b) Sarah's clothes are wet because she was walking in the rain. Sarah’s clothes were wet because she had been walking in the rain. 5-e) Julia was sleeping when a loud noise woke her up.