It is pretty well understood_______controls the flow of carbon dioxide in and out of the atmosphere today.
Many approaches have been _____ to control the spread of the terrible virus “Ebola” so far.
The failure of their friendship was closely related _____ other people’s privacy.
—Will Jane join in our party tonight? —Yes, but I’d rather she _____.
These trees must have been planted three years ago, _____?
Never should we forget the anti-Japanese war and sufferings _____ caused to people.