Great as Newton was, many of his ideas today and are being modified by the work of scientists of our time.
A. are to challenge
B. have challenged
C. are challenging
D. have been challenged
网友回答
A. are to challenge
B. have challenged
C. are challenging
(答案→)D. have been challenged
解析：challenge同ideas之间存在被动关系。句子表“当年牛顿的许多想法受到了质疑”之意。