Is _____ necessary to take off our shoes when we enter the computer lab?
The theory ________ by Einstein was later to prove true, but at that time few people could accept it.
The cakes are delicious. He’d like to have ________ third one because________ second one is rattler too small.
His studies on literature are very varied, ________ from Chinese literature to westurn literature.
The person who ________ advantage of the girl ________ a disadvantage didn’t gain an advantage ________ her .
—You like the Lenovo Computer. Why not buy one? —Well. I can’t afford ________ computer.