Each time, Billy Crystal performs his stand-up routine in front of millions of people when the show is broadcast _______ on TV.
There is no ________to what you can do if you try.
—Henry,________the light is ________when you leave the lab. —All right.
—________that middle school ________Beijing Normal University? —As far as I know,it is.
He opened the windows to ________ the smell of tobacco.
We don't have enough books for________;some of you will have to share.