Out ______ when the bell rang.
Many of us would agree that improving the countryside through technology has great potentials ______ food development in China.
It may not work out that one living in an English-speaking country will acquire the language ________.
An ideal job should be one that _____ what you are good at with what you are interested in.
Several underground stations are under construction at the same time these days, ________ the rush hour traffic even worse.
According to Charles Keeling, the amount of carbon dioxide ________ sharply and steadily over the forty years between 1957 and 1997.