His big book is an _____ of the little book he wrote before.(exp

His big book is an _____ of the little book he wrote before.(expanse)
【正确答案】：expansion
【题目解析】：由题意“是以前他写的小书的扩大版”和所给词expand可知，这里需要的是一个名词。故将动词expand改为名词expansion。答案为expansion。