During my visit to London, I took hundreds of photos. - WHILE - I took hundreds of photos ......... London.
while I was in
I didn't notice that my passport was mussing until I reached the check-in desk. - LOST - When I reached the check-in desk, I realised that ......... my passport.
I had lost
I've given up using the bus to go to school because it was always late. - USED - I ........ by bus, but I've given it up because it was always late.
used to go to school