—The light in the office is still on. —Oh I forgot . A. turning it offB. turn it off C. 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：表示忘记做某事，事情还没做，forget后接不定式。