Everyone, please remain ____ until the plane has come to a complete stop.
In doing scientific experiments one must be _______ careful with the instruments.
She _______ to the waiter whose language isn’t ______ hers to bring some more coffee.
As to the subject, we have consulted the most _______ professor who gave us _______ explanation.
“ Do you mind if I keep pets in this building?” “________________”
The headmaster could not go to the meeting; therefore, Mr. Smith _______ him.