The flowers his friend gave him will die unless ________ every day.
Who ________ that played a trick on the new English teacher?
—Where did you pick up the stamp?—It was at the post office ________ we worked in the summer vacation.
—Was it by cutting down staff ________ she saved the firm?—No,it was by improving work efficiency.
Is it that you often play computer games ________ worries your parents?
How time flies! It's in two months ________ we'll say goodbye to our high school life.