Mr. Green is said________ an experiment to prove their new method of solving the problem whenyoung.
A.to doB.to havedoneC.to bedoingD.to havebeen doing在线课程B
不定式作主补带有宾语及宾语补足语结构的动词变为被动语态时，原来的宾语变为主语，宾补则变为主补。