It may be necessary to stop______in the learning process and go back to the difficult points in the lessons.

— We are not allowed to bring any snacks to the sports meeting. —_____________.

Is this school ______you studied in threeyears ago

ung man, ______ severalattempts to break the world record in high jumping, decided to have anothertry.

I met Li Lei_____ hospital last Sunday. He was ill_____ hospital then.