A Choose the correct answer.1 I think I lost my wallet

A Choose the correct answer.
1 I think I lost my wallet while / during I was
walking to school.
2 I was still packing my suitcase while / when the
taxi arrived.
3 The underground station was flooded when /
during last nights storm.
4 The new airport was built during four years /
four years ago.
5 There was no place to park while / when I got
to the port.
6 While / When the passengers were sleeping,
a thief stole their luggage.