1) i/surf the net 2) mike/have lunch 3) daniel/already get to airport 4) sarah's clothes/be wet 5) julia/sleep a) when he/realise he/leave his passport at home. b) because she/walk in the rain. c) when we suddenly/have a power cut. d) and then do the washing-up. e) when a loud noise/wake her up.

1) I was surfing  the Net when we suddenly had a power cut.                                      

2) Mike had  lunch and then did the washing-up.

3) Daniel had already got to airport when he realised he had left his passport at home.

4) Sarah's clothes were wet because she was walking in the rain.

5) Julia was sleeping when a loud noise woke her up.

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.