Professor Johnson is said ______ some significant advance in his research in the past year.[1999]
【正确答案】 C
【答案解析】解析:It is said to do表示“据说做了……”,不定式的完成式to have done表示不定式的动作先于谓语动词前完成,而本句中的“去年的研究取得重大进展”先于“据说”,因此选项C正确。