The book is that one.
A. three time as long as
B. three times as longer as
C. as three times longer as
D. three times the length of
网友回答
A. three time as long as
B. three times as longer as
C. as three times longer as
(答案→)D. three times the length of
解析：考查倍数。书的长度不可用形容词long修饰，故用倍数+ the + n + of，根据句意选D。