3. He is teaching in his hometown now, but he________ in a hospital for 10 years.
With more forests being destroyed, huge quantities of good earth _____each year.
It is reported that the United States uses _____ energy as the whole Europe.
In peace, too,the Red Cross is expected to send help _____ there is human suffering.
Mr. Smith has bought a new house in the country, around _____ some green trees.
I'd like to have visited the Palace Museum last week, but something unexpected _____to my father.