Paper books still play an important role in the US textbook market, with digital textbooks less than 5 percent of the total.
A. posing of
B. making up
C. consisted of
D. accounted for
网友回答
A. posing of
(答案→)B. making up
C. consisted of
D. accounted for
解析：非谓语动词考查题。Make up 与digital textbooks为主谓关系用现在分词作补语。句意：纸质的书籍在美国课本市场仍然起着重要作用，数字书籍只占总数的百分之五。