At the railway station, the mother waved goodbye to her daughter until the train was ___.
The new library building _____ last week.
—Did you call Sara back? —I didn’t need to, _____ we’ll have a meeting together tonight.
Keep practicing and you _____ your English.
The air in mountain areas is ____ that in big cities.
Beijing is _____ capital of China and it is _____ city with many places of interest.