_____ human beings live in great numbers, the waters are very likely to become contaminated.
.I was about to leave _____ the telephone rang.
Children under 10 are not permitted _____ the film.
The bird hid _____ food inside trees for the winters.
We decided to ______ a chance on the weather and have the party outdoors.
.Excuse me, I have no ______ on me. Can you _____ the note of 100 yuan ?