The man kept silent in the room unless_______.
If you find yourself ______ no one will help you, please call me.
The government has taken some measures to solve the shortage of water, but it may be some time __ the situation improves.
— Why was it so noisy over there?— The Twins were surrounded by their fans ____ they stepped out of the hall.
Among the many dangers_________-- sailors have to face, probably the greatest of all is fog.
Mr. Black is willing to do ____________ Mrs.Black tells him to do.