—Where have you all day? —I came back at noon and I in this room ever since.A. gone; had

问题补充：

—Where have you all day?

—I came back at noon and I in this room ever since.

A. gone; had been

B. gone; was

C. been; have been

D. been; am

答案：

A. gone; had been

B. gone; was

(答案→)C. been; have been

D. been; am

解析：英语中表示一段时间的时间状语不能和瞬间动词一起使用，反之表示瞬间的时间状语不能是持续性动词一起使用。本题中all day和ever since都是表示一段时间的时间状语，即可排除AB选项。结合句意可知上下文都是完成时态，故选C。