My sister often helps me _______ my lessons.[ ]
Officials believe that more than one person _____ for the big fire.
I’ve ____ met her before, so I don’t know her.
Have you found your lost dictionary?—-No,I haven’t found_____,but I bought _______this morning.
At that time, he spent as much time as he can_______the ancient status which would be sank in the river.