With the fast development of puter and Internet technologies, traditional printed books by the growing popularity of online reading of e-books.
A. are challenged
B. have challenged
C. are being challenged
D. have been challenged
网友回答
A. are challenged
B. have challenged
(答案→)C. are being challenged
D. have been challenged
解析：考察时态和语态。根据句意可知本题应该使用被动语态，排除B项。根据句意可知传统的印刷书本正受到电子书的挑战。