问题描述：
this book is so difficult .he can it understand it 同义句转换
This book is ＿ ＿ ＿ ＿ to understand
This book is ＿ ＿ ＿ ＿ to understand
问题解答：
我来补答展开全文阅读
问题描述：
问题解答：
我来补答