—The light in the office is still on. —Oh I forgotA. turning it offB. turn it off　C. to t

问题补充：

—The light in the office is still on.

—Oh, I forgot

A. turning it off

B. turn it off

C. to turn it off

D. having turned it off

答案：

A. turning it off

B. turn it off

(答案→)C. to turn it off

D. having turned it off

解析：分析forget doing sth. 意为“忘了曾经做过某事”，forget to do sth. 意为“忘记去做某事”。