Jack, this is the third time that you have been late this week. —Sorry, sir, but I was _____ for 15 minutes on the way.

_____ he realized it was too late to return home.

The policeman warned the driver ________ so carelessly.

Listen! Is it Linda singing in the next room –No, it __________ be her. She is still in Shanghai.

Traffic restrictions have come into effect in Beijing ______to improve the capital’s air quality and traffic situation for the 2008 Olympics