They often stay up, reviewing their lessons, books all over the desk.
A. spreading
B. spread
C. are spreading
D. to spread
网友回答
A. spreading
(答案→)B. spread
C. are spreading
D. to spread
解析：books与spread之间是被动关系，spread的过去分词与原形一样。句意：他们常常熬夜，复习功课和看被铺满整个桌面的书本。