____the bus until it has stopped.
--- Do you know the reason _________ pilots turn off the plane’s lights before taking off? ---The practice is for the passengers to adjust to the dark _________ an emergency.
The Canadian dollar has fallen about 20 percent in value, making that dream ski vacation in Whistler Mountains __________than ever.
--- Sorry, honey. I’m afraid we are too busy to take a holiday at the present time. --- Could we take ______ two weeks from now?
China is a peace-loving country and under ____ circumstances ____ first use nuclear weapons.
being fun and good exercise,swimming is a very useful skill.