I DON’T KNOW WHY THE FRONT DOOR IS OPEN. I REMEMBER ___________IT...

19. - 25 DE THI HOC KI 1 MON TIENG ANH LOP 12 CO DAP AN
25 DE THI HOC KI 1 MON TIENG ANH LOP 12 CO DAP AN

19.

I don’t know why the front door is open. I remember ___________it before I left.

A. to lock

B. locking

C. to have locked

D. being locked