8.2 forget doing/to do

forget to do　忘記要去做某事?！?未做)
　forget doing　忘記做過某事?！　?已做)
　The light in the office is stil on. He forgot to turn it off.
　辦公室的燈還在亮著，它忘記關了。(沒有做關燈的動作)
　He forgot turning the light off.
　他忘記他已經關了燈了。　　　 ( 已做過關燈的動作)
　Don't forget to come tomorrow.
　別忘了明天來?！　　　　　　　?(to come動作未做)

典型例題
　---- 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：C。由the light is still on 可知燈亮著，即關燈的動作沒有發(fā)生，因此用forget to do sth.
而forget doing sth表示燈已經關上了，而自己忘記了這一事實。此處不符合題意。