His book is

网友回答

C 正常是than your book
省略了book 就要把your 变成名词性物主代词yours
======以下答案可供参考======
供参考答案1:
选C,比较级
yours指代your book
供参考答案2:
C后面一空要用到名词性物主代词
供参考答案3:
My book is boring ,how about ( d) A,you B,your C, yourself d,d,yours was happy past carefully until were was happy of quickly