The cells of humans, especially _____of the brain, can live only minutes without circulating blood.
The city was _____ to me, and I didn't know where to go.
The book is not _____ what we paid.
The thief ran away at the _____ of a policeman.
There are usually at least two _____ of looking.
My sister cleans the house from _____ to bottom when she is expecting visitors.