I seent 20 dollers or this book怎么改同义句? I ＿＿20 dollers ＿＿＿this book

题目

I seent 20 dollers or this book怎么改同义句? I ＿＿20 dollers ＿＿＿this book
The book ＿＿＿ ＿＿＿20dollers.

答案

楼上两位关于cost的过去式写法有误,应是cost （cost,cost)
原句写法应是：I spent 20 dollars on this book.
改写：I spent 20 dollars buying this book.
The book cost me 20 dollars.