______on ten years of observation and study, Professor Wang announces that everyone dreams every night, whether they realize it or not.
Traditional Chinese medicine is thousands of years old and has developed _______ time.
_______ with the Japanese government, some Chinese people decided not to buy products from Japan any more.
After I went abroad for further study, _______ of my parents lived with me.
When Helen saw her tutor nod _______ to her, she calmed down and went on with her performance.
Before joining the Department of Defense, Mr. Panetta _______ as director of the CIA from February 2009 to June 2011.