--Look! The light in the study is still on.
--Sorry, I forgot it off.
Aturning
Bturn
Cturned
Dto turn
网友回答
A. turning
B. turn
C. turned
(答案→)D. to turn
解析：考查forget的用法。 Forget to do 意为忘记去干某事 forget doing sth 意为忘记做过了某事 本句意为---看，书房里的灯还是亮着的，----对不起，我忘记去关掉它了。