题目内容：

forget to to do sth.与 forget doing sth.怎么用?
我知道：forget to do sth.是说：是还未做过的,后者是：已经做过的
但我还没弄懂这个定义的意思,
请帮我解释清楚
要是有例句就好了

优质解答

8.2 forget doing/to do
forget to do 忘记要去做某事.(未做)
forget doing 忘记做过某事.(已做)
The light in the office is stil on.He forgot to turn it off.
办公室的灯还在亮着,它忘记关了.(没有做关灯的动作)
He forgot turning the light off.
他忘记他已经关了灯了.( 已做过关灯的动作)
Don't forget to come tomorrow.
别忘了明天来.(to come动作未做)