——_____was the Nanjing-Changjiang Bridge open to traffic?——It was open to traffic in 1968.
I can’t quite remember ___ you started doing the work.
What do people in China often have __ dinner?
John was so sleepy that he could hardly keep his eyes ___.
--___ do you want? --I want a book on history.
Shortly after the accident, two ___ police were sent to the spot to keep order.