A survey of health researchers ______ that four hours of exercise every week ____ good for our health.
Americans eat____ vegetables per person today as they did in 1990.
Students ______ remain in their seats until all the exam papers have been collected.
The atmosphere of the earth ______ us from the strong sun light.
---How well did John do in the match? --Wonderful. I think we can’t have a ______ player in our football team.
Many countries are increasing their use of natural gas , wind and other forms of ______.