16. ---I am going to the supermarket to buy a quilt.
--- ________ You can easily buy one on the Internet.
A. Why not? B. Good idea! C. Why bother? D. By no means.
17. After _________ seemed like hours, a nurse wheeled Doris out of the emergency room.
A. that B. there C. which D. what
18. The number 911 is a special number, ________, I think, that will be remembered by the Americans forever.
A. what B. it C. which D. one