The students _______ busily when Miss Brown went to get a book she _______ in the office.
The housewe used to livehas been rebuilt.
In an experiment, pet owners are being encouraged to take their pets to work, a move _______ can be good for both the people and the pets.
By nine o'clock, all the Olympic torch bearers had reached the top of Mount Qomolangma, ___________ appeared a rare rainbow soon.
Is this the restaurant ___________ ?
She was so angry at all ______ I was doing ______ she walked out.