My friend, who _____on the International Olympic committee all his life, is retiring next month. [ ]

“Underground” is the only word in the English language _____ begins and ends with the letters “und”.

At the routine office meeting, the headmaster insisted that the problems ____________ paid special attention to.

well known that knowledge is ____treasure house, but practice is ___ key to it

Where___?—I got caught in the heavy traffic, or I ___ here earlier