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。