It was only after I came across that matter_______ how important it was to master a foreign language.
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.
Children under 10 are not permitted _____ the film.