Professor Johnson is said ________ some significant advance in his research in the past year．
A.having made
B.making
C.to have made
D.to make
网友回答
C解析考查非谓语动词的用法。Sb．is said 后接动词不定式，用不定式的完成式表已经发生的动作。此句相当于It is said that Professor Johnson has made some significant advance in his research in the past year．