1.What were helicopters doing as Yang Liwei returned to the earth's atmosphere?
What were helicopters doing as Yang Liwei ____ ____ ____the earth's atmosphere?
2.I am of the opinion that the dollar will be strong.
___ ___ ___ ___ that the dollar will be strong.
3.In the opinion of most people, something has to be done to prevent the air pollution.
In ___ ___opinion,something has to be done to prevent the air pollution.
4.He has experience at making kites.
He ___ ___ ___making kites.
5.He is keen to pass the final examination.
He ___ ___ ___pass the final examination.
6.The meeting was over at midnight.
The meeting___ ___ ___ ___ at midnight.