Some people may have been daunted by the task because of the difficulties it brings, but I do not know of______. A.them doing so B.any having done so C.their doing like that D.any doing that way
A. A.them B.any C.their D.any
【参考答案】
B 用any与not呼应,用完成式表示'至现在还不曾知……',所以应选anyhavingdoneso,相当于anywhohavedoneso。