2 I didn't meet my old friend while I was staying in Prague
I was staying in Prague when I didn't meet my old friend
3 I walked into a tree while she was talking...
She was talking...when I walked into a tree
4 I was shopping when he lost his wallet
He lost his wallet while I was shopping
5 I was doing the washing-up when I broke a glass
I broke a glass while I was doing...
6 I was driving home when they run out of petrol
They run out of petrol while I was driving...
7 I broke the key while he was trying to open the door
He was trying...when I broke the key
8 I wasn't swimming when we heard the screams
We heard the screams while I wasn't swimming.