Peter ________ at this job since he graduated from college.
She will tell us that each of us has a role ______ in making the earth a better place to live.
—How do you think he managed to improve his English in such a short time? —______ four hours on it every day.
In our ______,anyone ______ breaks the law should be punished.
Even on a cold day he prefers ______ out to play football ______at home.
It was in the lab______ was taken charge of by Professor Zhang ____ they did the experiment.