—This returned scholar has become one of the top experts in this field. —Yes, I know him very well. He ______ for ten years at an institute in the USA. A. has worked B. had worked C. worked D. has been working
According to the recent report made by the government, the number of visitors who have traveled to the earthquake-hit areas like Wenchuan in Sichuan has ______20,0000, ________to promoting their awareness of the disaster in hisrory.