Electronic devices such as iPods and headphones can do great harm to our hearing if _______ improperly.
The guide showed the travelers _____ of the factory.
We should mind our behaviour ______ public.
Excuse me, I have no ______ on me. Can you _____ the note of 100 yuan ?
They made a bet _____the white horse.
.I was about to leave _____ the telephone rang.