Letterboxes are much more in the UK than in the US, where most people have a mailbox instead.
The building around the corner caught fire last night. The police are now____ the matter.
The man who was being followed stopped from time to time ____ he wanted to tie his shoelaces.
He was found to be a thief, ____ disappointed his wife.
Every day the mother seems to be busy until 10 o’clock at night, ____the rest of the family have fallen asleep.