【题目】I rememberedthe door before I left the office, but forgot to turn off the lights.
A.locking
B.to lock
C.having locked
D.to have locked

【答案】B
【解析】句意：我记得离开办公室前要锁门的，但是却忘记了要关灯。A、C、D三个选项都表示动作已经完成。只有B选项表示尚未做。remember doing=remember having dong=remember to have done“忘记已经做过的事，忘记做了某事”。故答案选B。