The Smiths their breakfast when the doorbell rang.A. hadB. has been havingC. are havingD.

问题补充：

The Smiths their breakfast when the doorbell rang.

A. had

B. has been having

C. are having

D. were having

答案：

A. had

B. has been having

C. are having

(答案→)D. were having

解析：句意“史密斯一家正在吃早餐，就在这时门铃响了”。主语The Smiths为复数，主谓要一致，谓语也要用复数形式。